I think you could tell if you enable logging (Configure > Options) and restart PT4 and then try to import it and look in the log file. If you search for 'error' in the PokerTracker4.log file I think that will show you.
To find the log file go to File > Open User Data Folder in the PT4 menu, and then open the Logs folder in the window that opened.
If that sounds too complicated, or you can't find it in the log file then please attach the hud profile to a
Support Ticket and we should be able to find out for you.