Okay. So here's my experience.
Pereskiopsis don't have a lot of root mass, but they like to stretch their roots out a lot. I've recently began to prefer to put multiple in big pots because they grow way faster and are healthier when they have the extra leg space, so no, multiple pereskiopsis in a large pot is no problem.
Although, I have had masses of them in the same conditions in individual pots where most are doing amazing, but a few of them are barely alive. I'm not sure exactly why, but when I take those out of the pots vs. the healthy ones, one aspect is always the same. The root systems on the unhealthy ones are very weak and undeveloped. I'm not sure the cause, but you may want to give those pereskiopsis a nice root serum to stimulate their root systems. Healthy roots = healthy plant.
So no, the big pot with multiple peres isn't the issue. They actually do way better for me in big pots grouped together than in smaller individual pots. I get faster graft growth and more flowers on the scions and with no grafts I get a WAY faster growth rate for the peres. I can't say for sure what the problem is though, but you may want to do something to jump-start that root system!
New Wisdom