This is from promoted content on your site. (when someone clicks the promote button at the top of the topic). You can manage these by clicking your name on the front end of your site, then clicking "Manage promoted items"
There are no references to /community/ on the example you have just sent. I would advise on clearing your browser cache, as its very likely that is where you are seeing issues
Could you please confirm if you enabled or installed it? If just enabled, it seems you have had it installed before which may be what is causing you problems
If you take a look at the following location, this is all the developer documentation and API documentation 🙂 https://invisioncommunity.com/developers/
OK, it's the last part you are doing incorrectly there. Once you have uploaded, you want to go back to Site Features>Applications, where you will then see it available to install
Ah, now what I have seen there is you are moving these differently to me (I was going into the message and moving it from there). Could I confirm if its only happening from the list as you are doing? I feel we may be narrowing down the issue at least