Adding tags to an existing node using merge is not detected as a change and cannot be uploaded

[Simon Still]

Working on merge/conflation of the Transport for London Cycling infra database.

What steps will reproduce the problem?

1. Load a file of data ​https://github.com/cyclestreets/tflcid-conversion/blob/master/output/tables.osm.xml
2. find a 'table' and download OSM data for the area around it into second layer.
3. Select a table from tables.osm.xml, merge into the OSM data layer

What is the expected result?

The table is matched to an existing node and the tag traffic_calming=table has been added.

This should be seen as a change by JOSM which should then allow the change in the active layer to be uploaded to the OSM server

What happens instead?

the Upload button/menu item is greyed out and cannot be used.

If the tag is changed (edit, value=bump ok, edit value=table ok) then the change is recognised.

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

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-06-02 08:27:29 +0200 (Tue, 02 Jun 2020)
Build-Date:2020-06-02 11:11:35
Revision:16538
Relative:URL: ^/trunk

Identification: JOSM/1.5 (16538 en_GB) Mac OS X 10.15.5
OS Build number: Mac OS X 10.15.5 (19F101)
Memory Usage: 840 MB / 1820 MB (160 MB allocated, but free)
Java version: 1.8.0_251-b08, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 69731458 1920x1080, Display 722471565 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Djava.library.path=/Applications/josm-macosx/JOSM.app/Contents/MacOS, -DLibraryDirectory=${HOME}/Library, -DDocumentsDirectory=${HOME}/Documents, -DApplicationSupportDirectory=${HOME}/Library/Application Support, -DCachesDirectory=${HOME}/Library/Caches, -DApplicationDirectory=${HOME}/Applications, -DAutosavedInformationDirectory=${HOME}/Library/Autosave Information, -DDesktopDirectory=${HOME}/Desktop, -DDownloadsDirectory=${HOME}/Downloads, -DMoviesDirectory=${HOME}/Movies, -DMusicDirectory=${HOME}/Music, -DPicturesDirectory=${HOME}/Pictures, -DSharedPublicDirectory=${HOME}/Public, -DSystemLibraryDirectory=/Library, -DSystemApplicationSupportDirectory=/Library/Application Support, -DSystemCachesDirectory=/Library/Caches, -DSystemApplicationDirectory=/Applications, -DSystemUserDirectory=/Users, -DUserHome=${HOME}, -DSandboxEnabled=true, -DLaunchModifierFlags=0, -DLaunchModifierFlagCapsLock=false, -DLaunchModifierFlagShift=false, -DLaunchModifierFlagControl=false, -DLaunchModifierFlagOption=false, -DLaunchModifierFlagCommand=false, -DLaunchModifierFlagNumericPad=false, -DLaunchModifierFlagHelp=false, -DLaunchModifierFlagFunction=false, -Dapple.laf.useScreenMenuBar=true, -Dcom.apple.macos.use-file-dialog-packages=true, -Dcom.apple.macos.useScreenMenuBar=true, -Dcom.apple.mrj.application.apple.menu.about.name=JOSM, -Dcom.apple.smallTabs=true]
Dataset consistency test: No problems found

Plugins:
+ conflation (0.6.5)
+ jts (35122)
+ utilsplugin2 (35476)