Description
when merging multiple filters, sometimes conditions will not work. This is caused by mixing filters with different radio buttons "all conditions" vs "any conditions". Apparently the merged filter conditions internal "booleanAnd" attributes are not changed towards that of the target filter. So if the target (first) filter has "any" and the merged filter has "all" it may lead to some (or all) of it's conditions being to ignored.
Workaround: to fix such a filter change the condition from any to all, and save it, then change it back and save again. Unfortunately even though you can have mixed and / or operators for all conditions, the THundebird UI currently does not support managing down to this level. And it's very difficult to build a meaningful interface for building nested conditions, that is also easy to use.