I'm wondering if this has been resolved, if its maybe in the works for being resolved, of if maybe I'm going about doing something wrong.
Within the modulation section, if you try to assign a source via the hold source button, it only works once.
Try holding source, moving modwheel then assigning destination to cutoff.
Now try to do it as a second time but this time attaching mod wheel to osc freq. You can't access the mod wheel again from the mod source button. You have to find it manually which gets to be a bit tedious in the heat of the moment while patching.