Why don't packets go to VLAN on Mikrotik from the Internet?

Question

Computer networks

Good afternoon!
There are two identical subnets with XXX and UUU vlans on one of the routers.
With the same configuration, one has a ping and the Internet works, the other does not.
I can't post the whole config. (I'll do it later) But here's a general description:
-Filtering is normal without complex prohibition rules (drop is disabled and established connections are allowed)
-Both networks receive the Internet through the "router on a stick".
And now the weirdness! I tried to track Torch packets and even made two rules in the filter with these networks to look at the counters. So, the torch sees that the packets go from the Internet to the router on a stick and that they go from it to the router with vlans. And in In the filter, the counters see network packets with a working Internet and do not see them on a network where there is no ping.
Torch sees - there is no filter. There is no prerouting.
Where to look? What else could I have overlooked?

Answer 1

Nat?