Our 19’ Bus was leasing exactly like yours! Thought Lakefront got into my photo bank, LOL.
I found my leak by taking the garden hose on a dry day with low water pressure and ran around all the body seams “above” the side window. Wife inside the coach we found out the black Sika 221 sealant that was painted over but was not sealed well from the factory.
The water traveled down and entered the top corner of the window but it was actually running down from the top seal where the sidewall was seamed together.
I’ll dig for a photo where I taped off this winter.
Resealed the top and eliminated the leak.
Jeff & Gail
2019 Allegro Bus 40AP
2018 GMC Canyon Denali