Describe the bug
I send a sysex message to my Roland D-05 synthesizer to request a memory dump and intercept the MIDI input message with a callback function.

I've noticed that when the callback function contains any non-trivial code it doesn't finish running and the program can hang. Is this the intended behavior or am I doing something wrong?

To Reproduce
Here's the relevant bits of code:

def print_message(message):
    # Roland system exclusive messages
    if message.type == 'sysex' and message.data[0] == id_roland and message.data[2] == model_name_to_id['D-05']:
        channel = message.data[1]
        cmd = message.data[3]
        body = message.data[4:]

        print(cmd_to_str(cmd))

with mido.open_input('D-05', callback=print_message) as inport:
    with mido.open_output('D-05') as outport:
        outport.send(msg)
        input()

Expected behavior
The expected behavior is that this will print Data set 1, instead nothing is output.

If I change the print statement to print(message) then it outputs sysex data=(...) so I am definitely receiving a MIDI in sysex message.

Context (please complete the following information):

• MacOS 26.2
• Python 3.12.12
• mido 1.3.3
• backend used: python-rtmidi

Additional context
Experimenting with MIDI messages to program sounds on Roland synthesizers.