Unable to add entries via relational fields

[KBjana]

Describe the bug

I've just installed the plugin and set up the Many to Many fields and viewing data works no problem, but if you try to add an entry it appears to work, but it's not added to the source field. I've tried several similar plugins and reportedly this is an issue that's come up with all of them since the relational changes in Craft 5.3.

Steps to reproduce

1. Installed plugin
2. Create Many to Many field
3. Add to existing entry type
4. Open entry, I can see that it's picking up data from the source field
5. Add a new (existing) entry and save. The new entry appears to be there.
6. Open the added entry, the new relationship is not there.

Craft CMS version

5.5.2

Plugin version

4.0.1

Multi-site?

No

Additional context

No response

[engram-design]

I can confirm something strange is going on. It seems adding or removing items applies initially, but then after some time the entire field is wiped and the related entries aren't updated.

[stephenheron]

Yeah, we had a lot of problems with this plugin.

I had to get right into the code and change quite a bit of things to work like I expected it to: stephenheron@b02ae5d

Not sure if my changes will fix your issue's but it made it work for us.

[engram-design]

Thanks for chiming in @stephenheron that's at least a start for us to go off.

[engram-design]

Just applied those fixes for the next release. Fixed for the next release. To get this early, run composer require verbb/many-to-many:"dev-craft-5 as 4.0.1".