I don't have any trouble imagining how she could go OOA in this situation. Have done it once myself. Searching for an ornate ghost pipefish, found one at 15 feet at the very end of the dive. Thought nothing of breathing my tank down to dregs getting a picture. Diving wet, in tropoical water easy to ascend when the reg started to breath hard. No problem, a risk, but a very minor one. She was hunting weedy sea dragons. Could have found one - thinking she had something more than 10 bar - decided to get some last pictures on the dregs of the tank in very shallow water. In this scenario someone without drysuit practical experience could easily go OOA not even considering the impact of OOA on the drysuit.
Still should have been able to swim up, but if she went from horizontal to vertical to ascend while OOA with a wide open shoulder dump valve she would have been in immediate trouble with the only way to resolve the issue to dump weights at depth.
Not saying this is what happened, but an easy situation to get yourself into if your diving context is tropical.
Diving a dry suit is not hard, however, there are lots of little gotchas that you don't learn until you dive one for a while. My gotcha was having most of my weight attached to the backplate harness. Seemed to make sense until I had to remove the rig at depth to disentangle myself as part of a solo course. Looked like a balloon attached to the rig. Could not get back into my gear and had to surface holding the rig in front of me. If this had happened at depth for real and I had to abandon the rig i would go up like a rocket. Now I have a balance of weight on a belt and the BC so if I have to separate from the rig I and it are roughly balanced.
It is one thing to swim around in a dry suit, something else to dive one safely.