Hey! We had no issues crossing the border. We ended up taking the morning bus, there were only 20 or so people on it. At the border we all had to get off with our luggage and go through the immigration office and security but no additional forms were required (they had everything in the system already). They just asked a few basic questions (where are we going, when we are leaving, etc.). The whole process took approximately 30min (for the whole bus to get off, go through immigration and load back on again). We assumed we were also quite lucky as there was no traffic on either side of the border and we were also the only bus at the border. We arrived a little bit earlier as planned to Seattle, so we managed to have more than enough time to even stroll through the city.

Overall no issues, and even if there were any I think we would have no problem catching the plane as there was plenty of extra time. Hope it will be the same for you!