In many orgs hybrid is non-contractual and if employee refuses to WFO that could lead to disciplinary and/or performance management. To be on the sure side, is this employee responsive and productive when in office, or it just seems that way because they are there? e.g. not answering phones, disappearing constantly/lengthily, spending a long time doing other things like reading tabloid news or shopping or messaging? in which case presence in the office is not the ultimate concern. Also to tick all the boxes, Has it been checked whethere the employee has any issues at home? care, abuse, health etc.

I would just dismiss them.

In this case, I'm pretty much with Peter. Invite. Meet. Dismiss. Appeal.

In the wider context, if this person didn't have less than qualifying service, we do have a challenge when it comes to enforcing the physical attendance of remote workers. Of course, you can discipline them for refusing to obey a reasonable management instruction and that path leads eventually to dismissal. But an employer has to decide right at the start of the process if that's a game of chicken they are prepared to win.

In this case, of course, the employee is under-performing and it sounds like there must be a pretty decent body of evidence to support that assertion.

But if a business just wants someone to come to the office and they won't, but they are otherwise professional and productive, you have to ask yourself "am I prepared to dismiss an employee who is, in every other respect, doing the job I need them to do, just because they won't do it in the office where I want them?"

The answer may be "yes", in which case, proceed. But if the answer is "no", it is far better to acknowledge that in advance and just accept the status quo than to begin attempting to impose your will only to be forced into a corner from which there is no good way out.