Custom Module Related Objects

V 16.0.5
Does anyone have an idea why this would happen?

I ran into an issue when I tried to Link a Custom Module’s card to a Customer’s Proposal.

I’ll select one and click the LINK button.

The page reloads and the Proposal is not linked.

I also created a Sales Order for the third party and tried to link to the Sales Order and it doesn’t link.

I have also visited the Proposal and Sales Order cards I tried linking to and don’t see anything there either.

I reported this on the Dolibarr GitHub.