Sonos Era 100 original wall mount - problems

Hey guys, i hope somebody can help me solve this or can tell me what i do wrong :-)

Just installed my sonos original wall mounts for the Era 100’s. The wall is made out of concrete, so i used the provided plugs and everything went well.

Now i have 2 problems with both mounts it seems;

At step 6 i need to place the wall mount into the bracket on the wall and slide it down to “lock” it. Both of my wall mounts wont lock and they’re loose. I can wiggle and move them and this prevents me from positioning the speakers right. So the part with the speaker does not lock tightly with the part on the wall.

The 2nd problem is that the mount does not seem to hold the speakers weight well at the ball joint. I unlock the mount with a 90 degrees turn, then i position the Era 100 right and then i lock the mount again. The speaker will not stay in place and the speaker sacks down like its too heavy.

See these video’s for the problems: https://imgur.com/a/i5Vl9Ql

Thank you guys!