My Thunderbird Folder for Main Email (account) which is important, for some reason does not show my read emails upon next opening or when switching back from an alternative email (account) folder for which all are working properly. The emails are apparently there as there is a count figure at the top but I cant find anyway to selct them and I cant find any significant difference to the settings from other folders. I can only recall such read emails so far if i had "starred them" and select under Star works but only if they were "starred" I have tried "repair folder" but this has not made any difference.

Are you aware of such a problem? Please advise remedy