Did you solve your problem, I am having the same problem here.

Air gap acting as vent maybe , but who know you in the usa have weird regulations and are different every 5 blocks lol …

In Canada, floor drains have special provisions allowing them to be unvented. As long as the trap arm is 450mm minimum and the floor drain is not less than NPS 3. And of course, like every trap arm the drop cannot exceed the size of the pipe. At any rate, you could easily do this with venting to protect the traps.