Holding steady so far with new mobo BIOS 1.7, RGB Controller v.0F, and OLED Controller Version: v.0D. Everything seems to be working fine with all mobo LEDs, Rainbow LED connectors, and the Dynamic Dashboard II OLED.
As a brief synopsis: I used the MSI LED Update Tool to update the LED FW during mobo BIOS 1.2 to correct my Dynamic Dashboard II and Rainbow LED Header failures. I recently flashed the mobo BIOS 1.7 (using M-Flash this time instead of Dragon Center). I suspect Dragon Center may be contributing to some of the LED failure, but I have no evidence of this directly. I have purposely NOT opened Dragon Center since flashing the new BIOS and things seem to be working longer than in the past. I definitely won't be using it any time soon unless I need a critical driver from it--which is a shame because I would like to change the OLED display and Mystic lighting settings.
I think our collective advice here would be: don't update your LED FW through Dragon Center and (if you must) flash your BIOS using M-Flash. To their credit, MSI does generally warn the user not to update BIOS unless absolutely necessary, but the same rule could apply in the case of the LED FW as well.