As to that error message, Ignore it, probably not the cause.
When you say it is hanging, do you mean to say the import is still running and it is hung on a number 3358/18000? You can see the analysis number under Settings/Library
Or has the import finished and there are files missing.
If it is the later, then take a read of this:
https://kb.roonlabs.com/FAQ:_Some_of_my_files_aren’t_showing_up_in_Roon