Ah, ok. I see that the "will un-solo if sibling track is soloed" was fixed from the build I was using earlier, but it still can be a tad redundant having to re-solo the main track.
Perhaps Mixcraft could keep track of the solo-button order? If I click the solo button on Track 1, and then the solo button on track 1.2, then un-soloing Track 1.2 could keep Track 1 soloed, since Track 1 was soloed first. Comparatively, if no tracks are soloed and I solo Track 1.2, then Track 1 would automatically be soloed and would un-solo with Track 1.2.