Legacy Version Posts not Falling Back to BB Code

Hello,

We are running version 4.5 and have found that legacy version posts are not falling back to BB Code with the with WYSIWYG editor enabled. There is no formatting for legacy version posts and they are very hard to read. Disabling the WYSIWYG editor restores the formatting for legacy version posts. Please advise what we can do to fix this.

Thanks!

Mike