Simplify area is removing some big chunks

[naoliv]

Simplify area used to work so well but now I am seeing it removing some big chunks.
For example, with the attached area, JOSM's Shift+Y gives me a very good simplification but simplify area's Ctrl+Shift+Y removes a big area at the left side.

I even reseted the config values:

simplify-area.angle.factor	1.0
simplify-area.angle.threshold	10.0
simplify-area.area.factor	1.0
simplify-area.area.threshold	5.0
simplify-area.dist.factor	3.0
simplify-area.dist.threshold	3.0
simplify-area.merge.threshold	0.2

But had no luck.

JOSM:

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-09-24 21:53:10 +0200 (Sat, 24 Sep 2016)
Build-Date:2016-09-25 01:36:58
Revision:11051
Relative:URL: ^/trunk

Identification: JOSM/1.5 (11051 pt_BR) Linux Debian GNU/Linux testing (stretch)
Memory Usage: 516 MB / 10206 MB (100 MB allocated, but free)
Java version: 1.8.0_102-8u102-b14.1-2-b14, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900, :0.1 1280x1024
Maximum Screen Size: 1600x1024
Java package: openjdk-8-jre:amd64-8u102-b14.1-2
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-9
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

Plugins:
+ Create_grid_of_ways (32699)
+ ImportImagePlugin (32699)
+ OpeningHoursEditor (32699)
+ PicLayer (32796)
+ RoadSigns (32796)
+ SimplifyArea (32796)
+ apache-commons (32699)
+ buildings_tools (32944)
+ conflation (0.3.0)
+ contourmerge (1022)
+ download_along (32946)
+ editgpx (32699)
+ ejml (32680)
+ geojson (43)
+ geotools (32813)
+ importvec (32699)
+ indoorhelper (32680)
+ jts (32699)
+ log4j (32699)
+ measurement (32936)
+ merge-overlap (32699)
+ opendata (32898)
+ pbf (32865)
+ pdfimport (32796)
+ poly (32699)
+ reverter (32796)
+ scripting (30741)
+ todo (30000)
+ turnlanes (32796)
+ turnlanes-tagging (245)
+ turnrestrictions (32796)
+ undelete (32699)
+ utilsplugin2 (32815)