@golz - could you screenshot the current rule you have (from the rule builder, obfuscating any private data)? If you created it yesterday and there were tasks that should have been picked up, it might be a bug. One note: the due date approaching trigger will only fire if the specific day is met (i.e., due date is approaching in 3 days will not also pick up things due sooner, like 1-2 days out).
I think for your use case, you would ultimately want to add a second rule triggering on due date is changed, but your issue will be that there is no native condition for relative due dates (i.e., check if due dat is x days away). Consider voting for this feature:
You could check out using Flowsana to address this issue. The creator, @Phil_Seeman , is an active member of this forum and his tool does a lot of awesome stuff, including triggering when a due date is x or fewer days away. Check out his post here for more info: