I did tested the script, worked once and then it's not working so I do have the same issue. But then after a few button clicks, I get this window (screenshot) so I have no idea why it does that as I never done any scripting within OBS before. I'm not sure if it's a bug or not!

obs_properties_add_button's callback function should have props, prop as parameters, so the log will disappear if we change do_nothing functions as follows.

import obspython as obs

def do_nothing(props, prop):
    pass

def script_description():
    return "test"

def script_properties():
    props = obs.obs_properties_create()

    button = obs.obs_properties_add_button(props, "button", "Test", do_nothing)
    obs.obs_property_button_set_type(button, obs.OBS_BUTTON_URL)
    obs.obs_property_button_set_url(button, "https://localhost")

    return props

However, the same problem still occurs when I test it.
Also, when I tested it, it didn't even work on the first try.

obs_properties_add_button's callback function should have props, prop as parameters, so the log will disappear if we change do_nothing functions as follows.

import obspython as obs

def do_nothing(props, prop):
    pass

def script_description():
    return "test"

def script_properties():
    props = obs.obs_properties_create()

    button = obs.obs_properties_add_button(props, "button", "Test", do_nothing)
    obs.obs_property_button_set_type(button, obs.OBS_BUTTON_URL)
    obs.obs_property_button_set_url(button, "https://localhost")

    return props

However, the same problem still occurs when I test it. Also, when I tested it, it didn't even work on the first try.

Well... I have no clue whatsoever. If you have discord, you can go onto their server and put it into #scripting text channel under the Development category. People might be able to help better than me.

This is strange. It definitely should work. I can confirm the issue, at least.

Callback types must be manually implemented. Python functions are not C functions and cannot be passed directly as callbacks in the OBS api without implementing the appropriate wrapper.

The PR fixes the dialog box to appear when URL property button is pressed.
do_nothing callback is not called when button is obs.OBS_BUTTON_URL. I'm not sure if that's still the issue.