Annoying shifting issue with SRAM AXS Rival

After shenanigans with wheel and SRAM XDR freehub I finally got the bike after installing all the components together.

However I’m noticing a quite very annoying behavior of the XLPR RD. Everytime I try to use the 6th cog, the RD after a while switches itself to 5th one. There’s no green indicator on RD during that moment. It won’t occur while changing gear from 7 -> 6 – only when going to harder one (5 -> 6). However while changing from 7 to 6 I can hear the chain jumps a little on cassette. I’ve already tried to micro-adjust the RD but other cogs are starting to rattle on different settings (at the moment I have 19/29).

The hanger was already replaced in the process as the mechanic had troubles to adjust the RD on the original one which was on the bike. However it’s not a Specialized-brand one but a 3rd party one.

When I was picking up the bike I was told that there are some issues with changing from the 1st to 2nd cog (easiest ones) as the chain is not jumping onto it but only from this direction (1st -> 2nd).

New cassette, new chain. 1X configuration.