When I run ABackup it crashes whenever I select preferences. Sometimes it simply locks up. Other times it will throw amigaguide.library errors, sometimes ramlib errors. Sometimes it takes a few times selecting preference and quiting. If I go to my 4000D running a real old BB4, it works perfect.
I installed ABackup 5.22 from Aminet in an attempt to isolate the cause. The program and its Preferences are running fine here on my BB4 1.29 system, I cannot reproduce the problem. Therefore there may be some other cause for the issue you are having. ie. some other difference between your two machines other than the fact that they are running different BB4 versions.
Using old versions of BB4 is not something I would recommend as frankly there were quite a few bugs in those which have since been fixed.