Yes, the untrimmed looks good. The problem could be that cutadapt doesn´t accept returning trimmed samples with no sequences. It was just a guess, hopefully someone else will add some information on this 
I can recommend ITSxpress. Have a look at the tutorial Q2-ITSxpress: A tutorial on a QIIME 2 plugin to trim ITS sequences. 2 samples take about 3 minutes, so it takes some time. I ran it by night. However, DADA2 went much faster.