Can't load more than 3 imagery (background) layers

[pbb]

What steps will reproduce the problem?

1. Download some area from OpenStreetMap.
2. Add three background layers with satellite and other imagery.
3. Add a forth background layer.

What is the expected result?

The last layer should display just as the previous layers.

What happens instead?

While the layer is shown in the Layers window, it is not displayed on the map. Hiding the other layers does not help. But as soon as I delete one of the other background layers, the new one is displayed immediately. This connected to background layers; deleting the data layer does not help.

Please provide any additional information below. Attach a screenshot if possible.

I have this problem on two computers, while a third one (the oldest computer) does NOT have this problem.

System info from one of the computers having this problem:

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-02-26 23:10:22 +0100 (Sun, 26 Feb 2017)
Build-Date:2017-02-26 22:34:39
Revision:11639
Relative:URL: ^/trunk

Identification: JOSM/1.5 (11639 en_GB) Windows 10 64-Bit
Memory Usage: 197 MB / 247 MB (26 MB allocated, but free)
Java version: 1.8.0_121-b13, Oracle Corporation, Java HotSpot(TM) Client VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:<java.home>\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=%UserProfile%\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\56\1ee8cfb8-24c94ff3, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.splashport=62767, -Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp, -Djnlpx.jvm=<java.home>\bin\javaw.exe]
Dataset consistency test: No problems found

Plugins:
+ Mapillary (v1.4.2)
+ OpenStreetCam (53)
+ PicLayer (33148)
+ apache-commons (32994)
+ apache-http (32699)
+ gson (32680)
+ imagery_offset_db (33004)
+ mapdust (33044)
+ tag2link (33035)

Last errors/warnings:
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'

The following system report is from the computer that does NOT have this problem:

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-02-26 23:10:22 +0100 (Sun, 26 Feb 2017)
Build-Date:2017-02-26 22:34:39
Revision:11639
Relative:URL: ^/trunk

Identification: JOSM/1.5 (11639 en) Windows 10 64-Bit
Memory Usage: 769 MB / 1794 MB (504 MB allocated, but free)
Java version: 1.8.0_111-b14, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:<java.home>\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=%UserProfile%\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\56\1ee8cfb8-52c2697e, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.splashport=54866, -Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp, -Djnlpx.jvm=<java.home>\bin\javaw.exe]
Dataset consistency test: No problems found

Plugins:
+ Mapillary (v1.4.2)
+ PicLayer (33148)
+ apache-commons (32994)
+ apache-http (32699)
+ download_along (32946)
+ ejml (32680)
+ geotools (33042)
+ imagery_offset_db (33004)
+ jts (32699)
+ log4j (32699)
+ measurement (33088)
+ opendata (33156)
+ utilsplugin2 (33182)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/LaneAttributes&zip=1

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Sidewalks&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1

Last errors/warnings:
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'
- E: Failed to locate image 'https://dl.dropboxusercontent.com/u/4031522/foto/gst_icon.png'

[pbb]

The last loaded background layer does not display

[pbb]

Hiding the other layers does not help

[pbb]

The layer is shown as soon as one of the other layers is removed