I painted my 1964 colonial house last summer. It had a mix of old and newer paint. Scraped/sanded and full oil base primer followed by one finished coat of latex paint. There is significant peeling and bubbling developing and water drips out from behind the siding when I press the bubbles. There is a clear moisture problem as seen here:
https://streamable.com/8qpq4t

We did insulate the attic with closed cell foam a year prior to this as there is HVAC equipment in the previously vented/uninsulated attic. 

Some old timers I spoke with recommended using siding wedges to open up 1/8″ or so gap under the siding in the problem areas (they are spread around the house on three sides). Has anyone tried this? Any other ideas?