Z-Wave 5 second delays (Sending ABORT Message)

I’m running OpenHab 2.1 on a Rasperry Pi 3 and controlling my Z-Wave devices using an Aeon Z-Stick (Gen 5) and I’m having a lot of those 5 second delays when sending commands. If I e.g. switch a light four times in 20 seconds using Z-Wave, at least one of those commands will be 5 seconds delayed. I’ve also enabled the debug log to see what happens and I always find one of those messages five seconds after sending the command:

Sending ABORT Message = 01 03 00 16 EA

After that the command is sent again, an ACK is sent back and the light switches on or off. I’am also monitoring the serial_can channel of the Z-Stick and I’m currently having over 200 cancelled messages after just about 7 hours.

I’ve already tried to align the antennas of the Z-Wave devices better, but that didn’t improve the situation. Is it normal that so much messages are not received by the Z-Wave devices or is there a way to improve this situation?