The following links suggest AVIRA is known for false positives
https://www.google.com/search?q=avira+false+positives&oq=avira+false+positives&aqs=chrome..69i57.7280j0j4&sourceid=chrome&es_sm=93&ie=UTF-8
If you are having issues with using AVIRA on your PC preventing AI2 linkage, submit suspicious URLs; if you have apks that do not run without giving a false positive, submit the apk.
You said AVIRA identifies AI2 apk files as an issue? Are these just the apps you developed or ALL App Inventor files? If it is all App INventor files, you could write and compile a small program that trips the false positive and submit that (something that has a button and fills a label with the words "This is App Inventor and the apk is NOT malware." Be sure to include a friendly comment about AI2.
AVIRA is only going to listen to its customers, so you AVIRA users need to complain. Other reputable virus checkers are NOT identifying App Inventor apps as malware.
If this buggy software is bothering your experience and you have the free version, switch to another free checker. If you paid for it, complain loudly.
Regards,
Steve