If you use Multi-Rename Tool in Total Commander to batch-rename only folders and if all folders are numbered with dot after number (example attached and below) then multi-rename tool will treat all folders as filenames -- i.e. it will "see" everything before dot (two characters in above example) as actual filename and all the rest, after dot, as file's extension. Here is a quick fix for this situation (it actually may not be considered as bug).
I've caught this bug when trying to batch-rename a series of folders containing some of my photos. Since order of these folders was important and not based on alphabet, I have introduced numbering. An example:
In such situation, you can set
[N3-] or anything as name and you can try to cut-off even fifteen first characters and you'll still get only first two as TC "sees" this only as two-characters filename.
To solve this problem you should rather use
[=tc.fullname:3] in filename filed instead and you need to leave the
Extension field empty.