Strangely unavailable is one of the tells that remote workers might be up to something like that. One time I worked in a remote office that used to have just one person working from home in the area before the office was setup.
I could see she was upto something as she kept leaving the office for "meetings", stepping outside for phone calls and the like. She'd convinced hated office she was a really hard worker and always working late. But when you filtered here sent emails in Outlook you could see she stopped sending emails at about 5pm (leaving the office early for another "meeting" and then at about 11pm would reply to any email even ones she was just copied into to look like she was working late.
Company found her out about a year after Ieft. She had setup her own supplier to filter all the profitable orders to herself, also making counterfeit products of the companies products. She was the one responsible for gathering suppliers quotes so she edited them to make them more expensive than her own business so she would win. While dumping the unprofitable orders on other suppliers.