Hi @saatkinson! It looks like your barcodes and sequences files got swapped when you imported them into iowa_seqs.qza. In other words, barcodes.fastq.gz contains your sequences, and sequences.fastq.gz contains your barcodes. I verified this by exporting your multiplexed data with qiime tools export and inspecting the two .fastq.gz files with the less command.
Can you try re-importing your multiplexed data after you swap those filenames around?