Lots of unwanted duplicate groups and items

Hi all
since some time I have duplicates of all my groups in DTPO, one instance displaying the group icon, the other the tag icon. I am assuming that this is related to syncing between my Mac, iPhone and iPad but this is a gut feeling and not thoroughly tested.

Usually, they do not contain the same number of items and if there is an empty group (that should not be empty) it is the one with the group icon.
There are also lots of duplicate items inside the groups, too.

Before I go about trying to fix everything manually, how could I spot the source of the problem, fix it and avoid it happening again in the future?

Thanks

Screen captures would be helpful. If you don’t want to share them publicly, start a support ticket and attach them. Also include a link to this forum thread.

I created a support ticket with screenshots attached. I will report any solutions that are more widely applicable here if any.

If this has been happening for a few months it may be related to the bug in DTTG 3.5.7, which caused issues before Christmas, discussed in the forum (here, here). If that’s the case, I had it several times and running “verify and repair” on the affected databases and devices fixed the issue. It has not reappeared since so seems to have been thoroughly squashed.