Out of the blue when importing the Simbrief flight plan , it works on the EFB but when importing on the ACARS page of the FMS it brings up an old flight . I un-installed and re-installed via the Ini-manager without success . Any help on where to look for this problem would be appreciated . It is also occurring on one other add-on ( MSFS ATR42/72 ) in the exact same way which makes me think it's not a Windows/MSFS 2020 issue . Correct file ??

... sorry , I meant to say as it occurs on another add-on aircraft could it be a Windows/MSFS 2020 issue . 

Hi. Have you tried logging into and out of your simbrief account? Sounds like there is a caching issue on their end. 

Yes , along with checking user names etc . What clouds the issue is that the problem doesn't affect every addon . So far it's the Inibuilds A300 , MSFS ATR & MaddogX affected .  No problem with the PMDG  , Fenix or Blacksquare TBM aircraft .  Why does the EFB's have no problem yet the FMS's bring up the last flight plan loaded since the problem started . ACARS issue ?? I'd like to know where the INIbuilds A300 FMS flight plan is stored so I can look at the folder .

.... and the problem was with Simbrief downloader . Re-installed it and everything appears okay . Of course I didn't twig to the fact that some addons don't use downloader anymore .