Wow, the forum has changed, and I am not even sure that this post will land in the Collector forum.
In the past few days I have noticed that my point symbology looks fine in AGOL and on Collector's live maps, but as soon as I download a map on Collector to go offline, the symbols turn to "wing dings". I am running the latest version of iOS and Collector and this has not been an issue until very recently. Any clue why this may be happening?
On a related note, I noticed that popups will appear in offline maps on Collector even when they are turn-off in AGOL. Again, is this a bug?
Are you still seeing the issue for your service not displaying the correct symbols when taken offline?
The popups showing up when taken offline is a known issue with offline maps.