Curious as to what electroporation system you use? I always used an Amaxa, and 30M would have been a lot of cuvettes. Also, it was all about the program when it came to stem cells. It made all the difference.
"Nucleofector – Amaxa" and "Human Stem Cell Nucleofector Kit 1 – Lonza", I may need to play around with it though, as the protocol appears to have not worked very well (it was ~6M across 4 cuvettes, which may not be the optimal cell:cuvette ratio?...)
I used Mirus solution. It's been a while. That does seem like a lot of cells. For hMSCs, I'd do more like 500k per cuvette if I remember correctly, but they are big. Also, it was key that the volume was exact. I think it was 200ul. I want to say that I used the A-27 program, but I don't know if that is conserved.