Mikrotik, 2 tunnels not working at the same time?

Question

Mikrotik

there are 3 offices (A, B, C) - I attached the diagram in the picture
from office C to office A 2 tunnels were created - on the local provider through the intermediate branch B, and directly to the white address of office A.
office A has 2 providers, white IP on second provider (eth2)., the main one through which the tunnel goes through the local provider (eth1).
for some reason, if in office A the Internet goes through eth1, then a tunnel to eth2 does not rise from office C, and even pings do not go.
earlier at similar configs the tunnel rose.

Answer 1

There are no telepaths. I propose to start with guessing on the coffee grounds what kind of tunnel). We offer a variety of coffee.