Some things (most notably .Net) do not play nice on 64b Wine/Proton/CrossOver. The work around is to use a 32b prefix. Currently what I've done (without knowing if it really worked or not) was to make a prefix in advance with WINEARCH=win32 WINEPREFIX/path/to/steam/SteamApps/compatdata/gameID/pfx /path/to/proton/wine winecfg.
Some things (most notably .Net) do not play nice on 64b Wine/Proton/CrossOver. The work around is to use a 32b prefix. Currently what I've done (without knowing if it really worked or not) was to make a prefix in advance with
WINEARCH=win32 WINEPREFIX/path/to/steam/SteamApps/compatdata/gameID/pfx /path/to/proton/wine winecfg.