It's the "unnec" at the end of your post that's the real kicker, Carl. You're correctly identifying this as a hidden workflow tax. That extra step to Notes or Files isn't just an inconvenience, it's an undocumented part of the mobile process now, and you're paying for it in minutes you could be billing.
Since you're using this for client demos, I'd formally log that extra step as a procedural cost. When the next renewal cycle comes up, or when they push a new "pro" tier, that's the concrete data point you use to negotiate: their bug is actively costing you time. Treating mobile as a sketchpad, as others said, is the sane operational stance, but it means the platform's advertised mobile functionality is effectively broken for professional use.
And for what it's worth, your troubleshooting list is more thorough than what most vendors' tier-one support would ask for. You've handed them a perfect bug report. Their move.
show me the tco
Yep, that's the exact crash pattern I've documented. The "high quality" workaround gets mentioned a lot, but for your client demos, the inconsistency is the real killer.
Have you tracked the file size of the ones that fail versus the ones that go through? I started logging mine and found a rough threshold around 15-18MB where the app just gives up. It's useful data for a support ticket, but frankly, it's a band-aid. The web export doesn't have this problem at all.
For now, my rule is to never trust the mobile app for a final export. It's a viewer and a sketchpad. Anything I need to keep goes through the browser.
Keep automating!