Directory diff not working in TortoiseHg

[Florian]

I configured SemanticMerge in mercurial.ini as per https://users.semanticmerge.com/documentation/how-to-configure/semanticmerge-configuration-guide.shtml#HowtoconfigurewithMercurial,

resulting in:

[extensions]
rebase = 
mq = 
purge = 
extdiff =

[extdiff]
cmd.semanticdiff = C:\Users\My.Name\AppData\Local\semanticmerge\semanticmergetool.exe
opts.semanticdiff = $parent $child
cmd.kdiff3 = kdiff3.exe
opts.kdiff3 = $parent $child

[merge-tools]
semantic.executable = C:\Users\My.Name\AppData\Local\semanticmerge\semanticmergetool.exe
semantic.premerge=False
semantic.binary=False
semantic.args=-b=$base -s=$local -d=$other -r=$output -l=csharp -edt="kdiff3.exe ""#sourcefile"" ""#destinationfile""" -emt="kdiff3.exe ""#basefile"" ""#sourcefile"" ""#destinationfile"" --L1 ""#basesymbolic"" --L2 ""#sourcesymbolic"" --L3 ""#destinationsymbolic"" -o ""#output"""
semantic.gui=True
semantic.checkconflicts=True
kdiff3.executable = kdiff3.exe
kdiff3.args = $base $local $other -o $output
kdiff3.gui=True

[merge-patterns]
**.cs = semantic
**.** = kdiff3

[diff-patterns]
**.cs = semanticdiff
**.** = kdiff3

[tortoisehg]
vdiff = semanticdiff
  
[ui]
username = My.Name
merge = semantic

When I do a "Visual Diff" of two revisions from the TortoiseHG workbench:

• "semanticdiff" is selected as tool (as expected)
• The button to launch a "directory diff" is grayed out (<- This is what bothers me  )
• If I double-click a (.cs) file in the list, SemanticMerge launches and shows the diff
• This is also true if there are only .cs files in the diff

If I do the same with two revisions that differ only in one (.cs) file, SemanticMerge launches immediately.

How can I make the "directory diff" work?