Udev-Rule with "PROGRAM" statement is nor executed anymore after update to ubuntu 22.04.1 - udev

Question

I'm running a udev rule on my 3D printing server to automatically create easily identifyable symlinks to some attached microcontroller boards, which worked perfectly fine on ubuntu 20.04.
The rule triggers on the usb vendor and product ids and runs a python script via the PROGRAM directive. The script connects to the Microcontroller boards and reads it's init sequence to get the board's 'name'. It then outputs a string like "aaaaaaa b cccccc" and only the first block (containing the name) is used in the udev rule.
However, it seems like the whole PROGRAM directive is not executed at all anymore, since I updated my system to ubuntu 22.04.1.
My udev rule currently looks like this (While debugging. Regularly it just contained lines 1 and 3. I added #2 for testing purposes because the hook in line 1 works and that script is executed):
KERNELS=="ttyUSB*", ENV{ID_VENDOR_ID}=="0403", ENV{ID_MODEL_ID}=="6001", ENV{ID_SERIAL_SHORT}!="AI046A0Q", ACTION=="add|remove", RUN="/bin/su me -c \"/opt/me/deviceReg.py -d %k -a %E{ACTION}\""
KERNELS=="ttyUSB*", ENV{ID_VENDOR_ID}=="0403", ENV{ID_MODEL_ID}=="6001", ENV{ID_SERIAL_SHORT}!="AI046A0Q", ACTION=="add|remove", PROGRAM="/opt/me/serialUdev.py -s %s{serial} /dev/%k", SYMLINK+="%c{1}", OWNER="me", GOTO="script_end"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}!="AI046A0Q", PROGRAM="/opt/me/serialUdev.py -s %s{serial} /dev/%k", SYMLINK+="%c{1}", OWNER="me", GOTO="script_end"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A9QXPRV7", SYMLINK+="tty_MainSwitch", GROUP="dialout", OWNER="me", GOTO="script_end"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A9QOIMJ6", SYMLINK+="tty_Cooler", GROUP="dialout", OWNER="me", GOTO="script_end"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A9PTMHGV", SYMLINK+="tty_CurrentTransformer", GROUP="dialout", OWNER="me", GOTO="script_end"
The python scripts write to some logfiles which clearly indicate that only lines 1 and 4, 5 or 6 are executed.
Is there anything in line 3 that isn't supported anymore in the latest udev version? As I said, line 3 worked perfectly before I updated the system.
The last 3 lines are my current workaround. They work fine but that's not what I want to achive with this whole naming system at all.
The python script in lines 2 & 3 runs perfectly fine, either if called as standard user or as root. It would also deliver valid output if the '-s ' input data is not matching the uc board, is missing or is random garbage.
Does anyone have an idea why the script omits any line with a PROGRAM statement?

Answer 1

Ok, I was able to solve the issue.
I set udev's log level to debug too see what's actually happening when the device is handled. The script actually IS invoked but immediately failed during importing needed modules: The pyserial module could not be found.
The module is installed though, but obviously in a way it could not be imported.
However, I checked the python script again and changed the first line from #!/usr/bin/env python3 to #!/usr/bin/python3 and now it works again.
So my problem actually wasn't related to udev at all, it was just my python script.