Adobe Reader 11.0.21 crash on Windows 10 - what is the cause(s)?

We have some of our forms users with Windows 10 and 11.0.21 installed.  When they open our form in this specific version, it crashes.

The problem does not occur in 11.0.22.

We found the following: 11.0.22 Out of cycle update, August 22, 2017 — Acrobat and Adobe Reader Release Notes

Forms-XFA

• 4221443: Acrobat and Reader crash on launching some XFA forms.

Is more specific information available on 4221443 - what causes the application to crash?

The simple answer is to upgrade, but it is not simple to communicate this to all our users. 

Please advise if there are specific form features we can avoid using, so that our future forms do not have this issue. 

Our forms are long, and we want to avoid data loss.  Note: the issue is described as "Reacher crash on launching some XFA forms."

This is not accurate.  The form sometimes crashes as the user is part way working through it.