I have been struggling with this for the past few weeks as I am trying to develop some new styles. My problem first started when I tried to balance a style that used a supermidi piano.

The only way to ensure I got the mix i wanted was to check that box. Then regardless of any other setting the volumes will be set by the style. The default is 90. This overrides even realtracks.

If you also use the mixer window, and even the combo setting, the style seems to take precedent. You can alter the volumes, but the next time they load, you are back to the preset style volumes.

I use 2013, and I have only found 1 PGMusic midi style that has preset volumes (BOARDWALK) but there maybe others. Does BIAB 2015 have the box checked by default? It should be unchecked, I think.

PGMusic support tried to direct me through using a plugins including a limiter, to solve my problem, but it was just too technical just to get a style balanced

There seems to be so many ways to achieve the result, and they all interact. The BIAB manual (not the help screen) was somewhat useful but a little complicated. As with much of the documentation it explains the function but not the interactions. I found no reference to how style volume and mixer / combo volume work together.

BIAB for Windows Version 2019 (643)
Windows 10 (1909)