What drawer unit have you tried it with?
In my opinion it works best with the flexNT or flexDF.
It requires finding the sweetspot with the xNT / NExT
If possible, visit a local physical Ikea store, they should have the Idäsen drawer unit or cabinet on display with the Rothult lock mounted… try it out, bring the RFID Diagnostic Tool with you to make sure the batteries aren’t empty and the xFD Field Detector LED to find the sweetspot