May I know the OLS version? As long as the OpenLiteSpeed version is higher than v1.4.33, you should be able to upload it.
To upgrade OLS, run the following command,
Code:
sudo apt-get update
sudo apt-get upgrade -y
You can also check from OpenLiteSpeed Web Admin > Server Configuration > General > MIME Settings, and "image/webp" should be included.
If still not working, please share a screenshot of the failed information.