I've got  a list with 1400 items in it. All workflows are supposed to start automatically. I've found out today that about 700 haven't started at all. Not that they failed, but they never actually attempted start.

Some searching through previous discussion posts suggest file attachments name being the problem but I can say that doesn't look to be the issue here. Most of the attachments are variations of "firstname lastname.pdf" or like this specific case I have open now, the document is "KSS500_23443_20180130_105655656.pdf". 

I did notice that some days have a huger percentage of no workflow items. 2/7/2018 specifically had 30 items created, but only 4 of them had workflows. In fact, I haven't had any items created without a workflow since the following day, 2/8/2018, but there were a LOT of items without workflows in those 8 days of February. 

This odd pattern would suggest to me that we had something going on in our infrastructure causing this, but I have no idea what. Is there something else I can check on? Any other known problems that would cause a workflow to never start? 

Like I said, it's not that it failed or got stuck in a starting state; it just never fired off at all.