A user seeking for help in the german forum brought up the following.
If the number of thumbnail label lines is set to something different than 1, the filedisplay when showing thumbnails will not make use of the available lines to render the file labels. They only show in multiple lines after selecting the file and they will be visible as long as no other file is selected. Clicking the file display background to deselect all items does not do that (labels keep multi-line if the file was selected before).
This looks like something which is unintentional? The labels not using multiple lines is true for items names which do not make use of blanks it seems, but since even those labels show up when selecting items, it seems it's a quirk rather than some kind of technical limitation.
I'm currently having the same issue... I'm dealing with a lot of images and files that tend to have underscores instead of spaces and they get cut off when they would fit otherwise.
I was kind of hoping that adding "_" to the "wordbreak_char_names" in the Advanced options but only to find out that it only affects renaming.
I find it kind of inconsistent that one part of the program will recognize those additional word breaks while another doesn't.
Renaming is possible in some cases and for a few folders I've already done that, but at other time the filenames are formatted without spaces for web safety reasons because they are part of a website or other web project.
In those cases having to rename the files might break stuff.