New drive is not recognized after replacement

Recently drive 4 on my mycloud ex4 failed, bought a new identical drive 6TB/red for replacement.
After inserting the new drive the ex4 still shows NO/BAD drive in bay 4. Conecting the new drive directly to a pc it works perfectly.

Any idea what could be wrong? Could this be the SATA bridge? As I can’t even feel the new drive starting up.

That’s definitely a possibility…

Is there any place to purchase the SATA bridge individually?

None that I’m aware of. You might be able to find a replacement chassis on eBay or something (assuming your warranty is already expired).