Undo not working in motion

I don't know how many years this bug have existed that undo is not working or stops working in Motion at least when animating in 3d. This really can destroy hours of work. Is there any work arounds for this or anything you can do to prevent it ? Restart Motion makes undo work for some time then it stops again.

Imac5k late 2014 i7/OS latest/Motion latest/32Gb

Possibly the complexity of your project is overtaxing the resources of your computer making the undo unavailable. I haven't actually noticed that behavior. To avoid hours of work being lost you might consider adjusting the AUTOSAVE frequency which is set under the Cache tab in Motion preferences. This way you can limit any project corruption that might occur when UNDO fails you. You should also report to Apple if you haven't already done so.