I did some experimenting to try to further understand this issue...
I tried my MacBook Air which also runs Sierra but is not normally used for logging. I installed RumlogNG 4/2 build 316 and I could not repeat the problem.
However, after experimenting with my daily shutdown procedure, I can now make the problem occur on demand.
Part of my usual summertime (i.e. Lightning season) procedure in my shack is when I am done operating for the night, I turn off all equipment, disconnect all antennas and I turn off my 120V and 240V knife switches which feed the shack. I also disconnect my rigs from any computers (lessons learned. I took a lightning hit some years back and blew out the USB port on my TS590, along with the switch, router and cable modem) I do this with my K3 by removing the USB cable from the MacBook.
When I go to operate the next day, I plug the USB back into the MacBook, turn the K3 on. Before upgrading to Sierra, this procedure presented no issues. However, on Sierra, RumlogNG reconnects to the K3, but when I try to QSY from the ALL tab of the DX-spots window by clicking a spot frequency, it does not work. I must go to one of the band specific tabs in order for the QSY to work.
I tried it on both my MacBook Air and my MacBook. Works the same way.
My workaround is to quit out of RumlogNG BEFORE removing the USB cable when shutting down. When I do this, the problem no longer happens upon reconnecting. The only downfall of this workaround is that when I return to operate the next day, I cant see the history of spots because Rumlog no longer runs all the time. Not a big deal. I can view some Spot websites to see what is going on or I can do it the old fashion way and actually spin the VFO.
73, Ron WB2PKR