Is this a Pi 4-specific issue or is it an issue with the latest version of OSMC, even on the Pi 3?
Please reboot the device and supply logs:
To get a better understanding of the problem you are experiencing we need more information from you. The best way to get this information is for you to upload logs that demonstrate your problem. You can learn more about how to submit a useful support request here.
Depending on the used skin you have to set the settings-level to standard or higher, in summary:
reproduce the issue
upload the log set (all configs and logs!) either using the Log Uploader method within the My OSMC menu in the GUI or the ssh method invoking command grab-logs -A
publish the provided URL from the log set upload, here