I too have had all sorts of problems since the recent updates.
What worked for me was to go through each scheduled import and re-save them.
Go to edit and copy the URL and keep it handy, then delete that scheduled import.
Go to new import, select the type of import (scheduled) etc and paste in the URL and press preview. Then save scheduled import
Hopefully should work again.
If so will have to repeat for all your other scheduled imports