After enabling your plugin on my custom post type, it successfully removed the CPT base from the URL, but my custom post type posts are giving 404 when we use the non-www URL.
before this non-www was redirecting to www, and it is still working on my other posts except this CPT.
this mostly happens when your web is migrated incorrectly.
Sometimes people use shitty plugins like Really Simple SSL or others it can also cause many problems… or also some plugins that should migrate your website are problematic… migration is very easy, it should be done manually by someone who knows how to do it… you need to migrate your website correctly or in this case repair your wrong migration and everything should work.
You can search your database and I’m sure there will be many URLs with WWW and many without WWW – that’s wrong – it has to be fixed.