Text message anomoly Samsung S7

[SeldomFixit]

When I delete a text message thread from one contact and one contact only on my Samsung S7, I briefly see ANONYMOUS appear as the message is deleting. The user is in my contact list and this only happens with the one user, who's name and phone number are always viewable in the thread. Any other text thread being deleted happens with no hint of the aforementioned. I don't know that any nasties are in residence in my phone so somewhat confused. Any suggestions as to why are appreciated. Thank you. SF.

[Ancient Observer]

Maybe download ccleaner and run it? Could be something "leftover" from something else. ccleaner seems OK on my old S5 and current S9.

[SeldomFixit]

Thanks Ancient. Bitdefender found no fault but CCleaner is worth a go too. I'll try it