I purchased this addon mb339 in the store and it shows as credits, I uninstalled the mb339 due to CTD issues in FS but this was not the cause the AI issue was. Now I come back to reinstall MSFS market place shows it but no reinstall tab. On the microsoft store it is there as a credit and no link to reinstall. I am on the right account and I have an order number but all to no avail, this is not very goo of microsoft to not allow multiple downloads. Can anyone help?.
Hmm - have you checked in your “content manager” in the main menu?
I had a similar issue with one of the airports and noticed it shows up there.
So I would assume planes go there too. There should be a cathegory named “bought or owned”.
Typically updates and installs are managed in there 
Yes market place redirects me to content manager it is there and showing as owned but showing 0MB and no version number.
Does it say “Download available” for Mb339 item in Content Manager?
This is like an episode of Friends you know “the one where Joey is playing Charades” 
Hit “Alt” and “Prt-Scn” at the same time and I’ll make you famous, honest! - Alan Partridge 
It does now, I found the file folders and all were empty so I deleted them and went back to content manager and it was showing ready to download. So the folders being empty still showed as being there but 0MB. this my help other people who my have the same issue delete the empty folders and check again.
Nice one @RickyIIIIBobby glad you sorted it. I think this needs to be added to an FAQ or something. Hopefully the mods can take care of it. 
I would rather post is as bug 