Saved playermodels gets emptied after server restart from data/skinchooser_playermodels.ini
Tested on 2 servers (different hosting) with 3 versions (5.0-1-2)
CFG used:
https://pastebin.com/SsevxrNz
Easy to reproduce: Select a model, change map to save it, then restart the server, the data file will get emptied when you connect to the server.
Edit: Problem at line 614-615 where it creates FileToKeyValues into the ini file, and its get overwritten by it.