Our current CS Cart is a result of migration from a legacy 4.3.x so that may have something to do with this.
The problem is that all otherwise active addons show as "not installed" so we are unable to make any changes to them as the changes cannot be saved - the "Save" button does not exist.
The missing "Save" button and the permanently "Not installed" status affects newly installed addons too. Clicking on the "Install" button does nothing.
We have never faced such issue. It is required to examine issue on your server directly
I got a reply from CS Cart support. This was apparently caused by the migration. The installed addons lack a time stamp in the database. Hopefully support will be able to fix this ASAP as I lack the knowledge to do this.
Thank you for letting us know it
See this solution:
https://forum.cs-cart.com/topic/65121-paypal-shows-not-installed/
I tried this and it works