After you start Armory, in the bottom right is it showing as "Connected" in green? And is the number of blocks shown, equal to or higher than the block number that the missing transaction was included in?
Also, it would be helpful if you posted your Armory log files and advise the version numbers of Armory, Bitcoin Core and what OS you are running.
NOTE: To post your log files, please don't just try and copy/paste them into a post here, it'll be too long. Instead, copy/paste the contents of your armorlog.txt and dbLog.txt to
https://pastebin.com/ and click the "create new paste" button, then post the unique URLs that it generates for your files.