sieve auto-creation/subscription - Thunderbird cannot re-arrange folders

Hi guys.

In Thunderbird auto-subscribed folders - in my case a path with sub-folders - cannot be moved around, meaning top-bottom order. Parent folders Thunderbird shows in cursive and sub-folders (targets for sieve fules) are shown "normal" It seems impossible to re-arrange top/parent folders - but every other folder, top or not, which is not auto created & auto subscribed, Thunderbird can move around as expected. Anybody seen, anybody knows this and knows a way to "fix" it?

many thanks, L.