Not receiving codes from remote buttons

[okaapi]

I am not receiving repeatable codes/signals from two different RF remotes (Surnice, Smartwares - both specify 433.92MHz).

In the following dump, two or three actually happened at the same time as a button press, the others are noise?

For sure, I am not able to reproducibly get the same code if I press the same button (mostly there is no code when I press a button):

> 2023-01-03 06:06:38 - [INFO] rpi-rf_receive: 1 [pulselength 1538, protocol 2]
> 2023-01-03 06:06:48 - [INFO] rpi-rf_receive: 2 [pulselength 863, protocol 2]
> 2023-01-03 06:07:36 - [INFO] rpi-rf_receive: 4 [pulselength 1260, protocol 4]
> 2023-01-03 06:07:46 - [INFO] rpi-rf_receive: 31 [pulselength 83, protocol 3]
> 2023-01-03 06:06:38 - [INFO] rpi-rf_receive: 1 [pulselength 1538, protocol 2]
> 2023-01-03 06:06:48 - [INFO] rpi-rf_receive: 2 [pulselength 863, protocol 2]
> 2023-01-03 06:07:36 - [INFO] rpi-rf_receive: 4 [pulselength 1260, protocol 4]
> 2023-01-03 06:07:46 - [INFO] rpi-rf_receive: 31 [pulselength 83, protocol 3]
> 2023-01-03 06:09:06 - [INFO] rpi-rf_receive: 512 [pulselength 1952, protocol 2]
> 2023-01-03 06:09:54 - [INFO] rpi-rf_receive: 2 [pulselength 2273, protocol 4]
> 2023-01-03 06:10:18 - [INFO] rpi-rf_receive: 8704 [pulselength 1672, protocol 2]

I have only the receiver connected at this point - can't imagine the transmitter is required to make the receiver work.

I have no problem recording the codes from the same remotes with a Broadlink RMPro - so it's not a problem with the remotes.

I tried modifying the rx_tolerance (0-1000), made no difference.

Any pointers would be appreciated!