I cannot enable File sharing and other sharing services
I'm trying to enable File Sharing through System Preferences -> Sharing but the checkbox next to the File Sharing service doesn't respond: clicking on it does nothing, it does not check it (and the service remains off). The same is true for Media Sharing, and Internet Sharing (whose checkboxes look slightly greyed out). See the attached screenshot.
I'm on a macbook pro 13-inch mid 2018 running macOS 10.15.7 (19H1922) (latest updates).
I have tried resetting SMC and NVRAM but it made no difference. I've tried it in safe mode, and there's no difference.
What could be the problem and how can it be fixed?
MacBook Pro 13″, macOS 10.15