Kohler Persuade Flush Problem (Brand new toilet)

Just replaced 3 working toilets as part of a remodel. All 3 are Kohler Persuade Dual Flush. Two are working fine but the 3rd one will not empty fully during flush before refilling. It goes through the normal flush routine and and a moment before the water is about to empty from the tank it starts refilling (during #1 flush). #2 Flush works correctly about 60% of the time. Kohler support immediately offered a refund / replace but this is holding up my remodel and I do not want to wait a week or two for another. Plumber tried the following:

1. Snaked the drain (3") and ensured trapway and vents are clear.
2. Replaced wax ring with one without a collar
3. Tried various settings on the canister valve
4. This does have an offset flange but so does another toilet which works fine.
5. Filling the bowl with bucket of water flushes down normally.
6. Swapping canister flush valves with working toilet, same problem (working toilet still works fine with this canister valve).

Running out of options and would really appreciate any advice you can give.

Sam,
Sounds like something lodged in the trapway of the bowl. A closet auger may clear that.
Sometimes during construction, people use the toilet as a waste basket. Not good.

Probably what Terry said, but, it still could be a defect inside of the toilet.

Just ran into this exact same issue and what I found was the plungers on the flush buttons (on the lid) were not set low enough. These plunger rods are threaded and adjustable. Hope this helps someone, I spent a lot of time troubleshooting like the OP.