If anyone comes across this post and is in a similar situation, I needed to use the ’ Apt - Rebuild Apt metadata’ task described on this page Tasks (sonatype.com).
This task is hidden unless nexus is configured with a postgres backend as posted here - Missing “Apt - Rebuild Apt metadata” - Sonatype Nexus Repository - Sonatype Community
I changed my backend database to postgres, ran the task and was able to pull from my apt repository.