Here's what happened for us last week. I did the prepurchase MM at $149 and linked it to our MBs.
I was a little worried about it but felt confident with the photographers as they did seem to be making sure something was happening each time we had our pictures taken.
We had some time to kill before an ADR at Ohana and I decided to look at our pics since they have a Photopass location at the Poly. Glad I did. All of our regular photos were there but none of the attractions photos were showing up. Great CM made a call and magically they appeared. This was Wednesday.
On Thursday we were at HS and had ToT and RNRC pictures taken. Towards the end of the day I checked our pictures at one of the Photopass locations. No attractions photos. That CM was a different story. She made no attempt to help and handed me a business card for the Photopass Help Desk. I called, they told me to give it 24-48 for the photos to show up. They said they couldn't see them.
Sunday after arriving home I downloaded all the photos. No attraction photos from Thursday or Friday (also a HS day). Disappointed. Help Desk not open on Sunday.
Called Monday, 35 minute wait, no thank you.
Called yesterday, yes, after a few minutes the CM was able to find the photos and link them to me.
I honestly have no idea what the problem was. I tried to explain that the same thing had happened while we were there. It seemed to be a recurring problem with attraction only photos. She was interested but really was helpful and nice. I think she just didn't know what to say.
Will I buy Memory Maker again? Probably. Last year they lost my treasured Gaston photos (LOL) and they were never recovered. We like the convenience and it worked out well since it was just the two of us this time.
My recommendation would be to check the photos everyday and make sure everything is there and get it resolved while you're in the park.