I avoid using any potting mix that has the word "soil" in it. My plants from seedlings to pot ups don't touch, taste or feel any soil until they get into the dirt. Any soil mix will retain too much water, this also causes a lot of, crap a can't think of the name of it, I guess I'm having a senior, drinking moment, what I'm trying to say is that the stems will rot at or near root level. Dang, I can't believe I can't remember the name of the root rot problem. I need some youngsters to re-educate me.
Are you using MG Potting Mix or Potting "SOIL"?
Had another drink and dang it, I remembered. Damping off is the problem you could potentially have with soil or potting mixes that are too wet.