I am using python and python-can to send messagesreceive and process messages from a CAN bus which I create like this:

bus = Bus(interface="pcan", channel="EXT_CAN", bitrate=500000, receive_own_messages=True)

The bus object is then passed down to a class that connects to that bus and implements the sending / processing:

def connect(self, *args, **kwargs):
        """Connects to bus. Expects "bus" as keyword argument."""        
        self._bus = kwargs.get("bus")

The class also implements a method for waiting for a specific message:

def wait_for_message(self, can_id: int, timeout: int):        
        self.time_start_listen = time.time()
        expected_message = None
        while time.time() - self.time_start_listen < timeout:
            msg = self._bus.recv(timeout=1.0)
            if msg.arbitration_id == can_id:
                expected_message = msg
                break
        assert expected_message

While testing this method, I have noticed that sometimes, the expected message is simply not picked up and the method raises an AsserionError.

I am using PCAN Viewer in parallel and I can see the expected message on the trace, so I am certain the message is actually being sent.

For reference, this is a cyclic message, with a cycle time of 1s.
There are several other cyclic messages on bus, with 20ms cycle times.

The timeout argument in the wait_for_message method is large enough to capture at least one frame of the 1s message. This also checks out on the timestamps of the messages I do receive. However, the 1s cycle time message is sometimes skipped.

Has anyone experienced this behavior? What can be causing this?
Any hints are appreciated. TIA!

Also tried replacing the

while time.time() - self.time_start_listen < timeout:
    msg = self._bus.recv(timeout=1.0)

with:

for msg in self._bus:

but the behavior is the same.