This problem has plagued me for years, and has been reported multiple times to Evernote in these forums, and I've yet to even see a response from anyone at the company. It's extremely frustrating, but seems to be a problem that Evernote neither cares to acknowledge or is determined to fix.
It's not rocket science...I use any number of other note or word processing apps, and those apps seem capable of counting from 1 to 10 (or whatever number of items in my lists).
When it's real bad (and with anything approaching a complex list, there's a better than 80% chance that it will happen), it gives me that, "Why am I paying for this again?" feeling...
Do better, Evernote (if you're even listening).