Also purchased the IQ+ 2 weeks ago . 2nd downhill I parked on, brake didn't engage. Luckily no runaway cart or ending up in the dam. Will need to see if anything can be done about it. For now I just make sure to park level
/update : Went to have a look to see if the holding pin can be pulled out a bit as it protruded only about 0.5 cm when locked. Did so and it extends now almost a full cm when locked. Perfect, no runaway cart any more