Changing the plan issue source results in resetting excluded versions list

Issue Summary

Changing the plan issue source results in resetting excluded versions list. It is a major problems for customers who try to create a plan across multiple teams.

This is reproducible on Data Center:

Yes

Steps to Reproduce

1. Open an existing plan
2. Go to plan configuration > Exclusion rules > Exclude releases
3. Select a release to be excluded from the plan
4. Go to plan configuration > Issue Sources
5. Add a new board or project
6. Go to plan configuration > Exclusion rules > Exclude releases

Expected Results

There is at least one release in the list of excluded releases.

Actual Results

The list of excluded releases is empty.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available