I've found it difficult to monitor, train, and help the employees that work under me. What would normally be just 10 minutes of me sitting next to them and going through some things, has turned into an hour of frustrating screen sharing etc.
I also had one employee that was clocked in over 8 hours a day but producing almost nothing. I'm quite certain he was not working.
I have one employee that just started right before COVID hit and training has been extremely difficult. I normally would have the trainee sit by my desk and watch me work for a while to get the hang of things, explain what I'm doing while I'm doing it, and have them listen in on calls.
I myself can work from home with practically the same productivity, but it's hard to train, monitor, and guide remotely.