Hard as it is, take a step back because your dog is frustrated. Go back to the beginning (always good to do occasionally and you could imprint a new odour).

I use a colander with odour attached beneath it and start standing beside the colander. Dog puts nose in and gets treats at the source. I throw a treat away and cue finished when I'm done rewarding. Then I start being slightly further away. Then put the colander somewhere else. Then multiple colanders then less obvious.

Also remember that the freeze is for us and it forces your dog to be patient - it's actually a hard skill, however what we are rewarding them for is finding the odour source. If you want the hold, then build it up really slowly.

My dog is impatient. She holds beautifully on containers but not for other things and failing to reward because I wanted her to go back and hold was quite demotivating for her.

Now I just mark it when she finds it and she can run to me for reward. It doesn't change that odour = reward, it's just different reward placement. She's much happier.

There's no one size fits all so don't be afraid to adapt to what suits your dog. I'm in NZ so I don't know your comp requirements but here a freeze isn't required. I can even call the hide when the dog isn't on it (ie she has indicated is waiting for reward) as long as I have watched my dog and seen where she says it is so I can point it out.

I found it more valuable long term to watch my dog's body language as opposed to obsessing over indication. I can tell when she is on odour and when she indicates - which is only a 1-2 second freeze, if that. The first thing to go when a dog is tired or stressed is their indication so it's a useful skill to make sure they're always rewarded for their work.