how did you setup this URL?
Can you send me instructions how can I replicate your environment?
I mean … whether you use some CPT plugin or manually write code to create taxonomy and CPT, what is your Permalink settings, etc…
Can you test this?
Unzip it and replace /wp-content/plugins/remove-cpt-base/remove-cpt-base.php
Let me know, it should work I just tested it, so if you confirm it, then I will release new version 5.3 😉