If you think it is a problem with the nutrients, look for a fertilizer that is high in Phosphorus. That is the middle number in the nutrient rating (NPK). But, it could be that you are giving to many nutrients. I have only added fertilizer to my peppers in containers twice this summer and they are doing great. That MG raised bed mix likely had a good dose of built in nutrients.

Leave them alone and read a book.....they know what to do.

You have a problem and it is more likely due to disease than fertility. Fungal diseases will only get worse if you don't take action to control them.

The mix was a disappointment in that the drainage was not great - retained too much moisture. I have been using the tomato plant food from miracle-gro to supplement the
plants.

Is there anything I can do to stop the drop and/or encourage more blooming?

Water problems: get a moisture meter and learn how to use it. Water when the soil needs it, not when the calendar says it's time.

Don't over fertilize: it leads to lush leafy grown and fewer peppers.

What is in the "miracle-gro raised bed mix"? It sounds like it's meant to have a lot of slow-release stuff, and peppers are not heavy feeders.