DB open error (MDBX “unknown error code: 11”) when running rbuilder separately from reth

I'm encountering a recurring DB open error when running rbuilder as a separate container alongside reth. My setup mounts the Reth database directory (and IPC path) into the RBuilder container in read-only mode. However, I keep getting the following error in the logs:
```
Error: DB open error

Caused by:
0: Could not open database at path: /data/db
1: failed to open the database: unknown error code: 11 (11)
```
appears that MDBX does not allow two separate processes (reth writing to the DB and rbuilder also opening the same DB) without conflict.

From what I understand from the documents, reth should be run as a separate process from rbuilder. Can someone explain exactly where I am making a mistake?