rpmemes-galore:

A small PSA that tumblr is no longer only having issues with showing acivity, it’s also taken to eating asks at an alarming rate. So, it may not be a bad idea to message your partners and ask if they’ve even received the memes and messages you’ve been sending them through the inbox, because it seems like most people, unfortunately, are not. 

edit: there’s a post here that explains and gives you a good way to check if your own blog has been missing asks sent to it.