Does the noise sound more like a rattle ? Or knocking.
No expert but had a similar issue with mine giving off a rattle onced warmed up and idling same BWA engine, had the timing chain and tensioner change, that got rid of the noise for me. Another part the adjuster is a recommended part to also have changed but costs are £350+ just for the part so I left it out.
It could be that yours has failed. Unless you also had that changed?