Hello - I am also having this same issue. This is my first ever field maps that I've created, and first collection I've ever managed, so I'm figuring this all out from scratch. Our field crews are attaching upwards of 20 photos per point. They asked if they could take the maps offline, and I want to tell them yes but I've been testing and having these same issues mentioned above.
They are adding points along a line that runs a few hundred feet, so decreasing download map size doesn't seem tangible. I attempted various suggestions from above, none are working for me. Just for troubleshooting purposes, I played around and downloaded down the size of a neighborhood parcel and that failed.
I figure it's been 2 months since the last comment on this post. Does anyone have any updates or suggestions? Again, brand new, any and all advice/suggestions are welcome.