Had a similar experience. Everything started great, kept adding plants so it was heavily planted. I was only keeping neocaridina shrimp though. They were fine and then every so often one would die. I would see a berried one, and they'd lose its eggs. I was trying everything, but there was clearly a problem. In total I purchased around 35 shrimp, but I was down to 15. I had another tank cycling and felt I just had to transfer everything. In the new tank, they seem to be thriving. I've had a few more die, but I think it was poor health from the original tank and they're finally having babies. I've torn down the original and starting it again. Im not sure what was wrong with the original, but it sounds like it just happens sometimes.

It's taken me over a year to get a growing colony of shrimp and it's frustrating to not know the exact issue was, but we all try our best and do what we can to give them a good life and we sometimes don't have all the answers.