Came back after some time and me and my friends' characters are missing

Hello,

We haven't played Wow for over a year and redownloaded now. After logging into our MOP accounts, there are no characters. However one friend which didn't delete Wow files (still hasn't played as long as us) joined in and his character is there.
What could be the reason our characters are missing? There is no way any of us manually deleted them, they were max level. Anyone else had this issue or something similiar?

There have been inactivity purges that likely occurred during your absence. Premium accounts I believe are spared from character deletion and renames.

. .

Only up to level 50 inactive characters gets deleted. Inactivity Cleanup and Gold Squish for a healthier economy

Sounds like your accounts got cleaned by somebody. "But nobody had access".. that you know of.