Strange behavior of sms counter

[anton_om]

In my xperia C5 default sms-application always show that one message was't read. Even if all was readed. Even if there are absolutely no messages inside.

I've tried to reset this application and clean the cash from settings. And it helps for a while, but after any incomming message problem appears again. 

[anton_om]

@Christofer and finaly - nope. "eraser" app doesn't help.

Full factory reset doesn't help as well.

I've stored all data with Sony PC Companion 2.1. m.. I mean I'm think that I've stored all data. But it is not true, actually this feature seems doesn't work. Because after restring I still need to setup my phone manually. Remove unnecessary icons, install all applications, and etc. Only one good thing - my contacts are not losted.

And result is zero. Nohting help. Default messenger still show that one message is not readed. I don't want trying to solve this issue anymore. Actually I think it just a software issue specific for this phone.