Why are apps, text messages and Whatsapp messages all disappearing from my S7?

[Android Central Question]

Every couple of days my Samsung S7 loses all text messages, all Whatsapp messages, and even some apps disappear entirely. Only contacts seem to remain, but almost everything else is gone, save for select applications. There is no SD card installed, everything is on internal memory. The phone is up to date (as of April 2018 update), however the problem persists. Text messages will remain for a couple of days, and randomly I will check and they will all have disappeared. Whatsapp messages also disappear. I installed a call recording app 5 times, and it works for a day or two, and randomly disappears as if it were never there.