Accessing BR1 while IP passthrough is enabled

We have a number of BR1’s that are connected up to other routers on site and the BR1 has been set to use IP passthrough which it’s doing perfectly however, we have found that when the IP passthrough is enabled we are unable to SSH to the 10.xx.xx.xx address, if we disable IP passthrough, straight away we’re able to SSH.

Does any have any suggestions how to resolve this?

Thanks!