HP Z6G5 with installed TBT4-340L1AA boots twice

[TimLo1]

HP Z6G5 workstation with OS Win11 23H2. TBT4 HP 340L1AA is installed and works as expected.
However, each time the PC is switched on (if the power source switched off after last use) it boots twice. The power lamp first is on and after a while it goes off and a second later it goes on again and the OS starts. This behavior was not observed before the Thunderbolt 4 card has been installed.

If the Crate is left connected to a mains plug switch on, it will boot without issue. Issue persists if crate disconnected from power source.

I have seen this issue reported previously and a suggested workaround regarding disabling fast startup (which did not work for me). Is there any further information on resolving this issue?

Thanks.

Tim

Thanks for any helpful comments.

[TimLo]

If anyone is interested, I found the solution. Take the bl**dy thing out! Despite being sold as compatible with Z6 G5 machines, it causes a significant error.