I created a custom table /Tender/ for which I enabled the connections, to create fuzzy relationships between two rows. After enabling it the relationships /connection to/ and /connection from/ were added and I was able to see the table in the connection role list. But when I open a record of that custom table /Tender/ I don't see the ribbon button /Connect/ to create a connection. Through the related tab I can open connections and see the connect button there. (see image). I tried creating a connection through that with an account and was able to save it. But the created connection does not show up. When I navigate to the account record, the connection is visible there. Now when I want to create a connection from any other table with my custom table it does not work. I the record list my custom table does not show up at all.
After some research we found the config for connections and looked into the metadata of the custom table. The setting IsConnectionsEnabled was set to TRUE, so that was correct as well.
We tried creating new custom tables but with the same result, that /Connect/ does not show up in the ribbon and connections can't be created to the new custom table.