The Drafts app wasn’t appearing when editing the list of apps of the share sheet on iPhone. I rebooted and it reappeared, along with several other apps. It’s an annoying iOS bug.
I’ve been paying attention to this over the past few weeks, and it seems that if OF is missing from the share option, it will always reappear once you dismiss the share, and try again.
Thanks for the tip. I haven’t been able to test it thoroughly, but your workaround seems to work for me. One caveat though (and again, I have not been able to test this thoroughly yet):
If I dismiss the share sheet by tapping above the share sheet, OmniFocus still won’t be available when I tap the share button again. If I dismiss the share sheet by tapping the X button, then OmniFocus will appear the next time I tap share.