Odd.. yeah I have 10.12.1 PB4 on a 2013 iMac, 2012 MBP, 2010 MBA and the machine I'm on now, a 2015 rMBP and none of them as experiencing this.. I guess use Firefox for the time being!
huh. it IS odd. and since i have 2 macs (and one CAN get on musicgateway), both on the same OS version... i can't figure the common denominator. at least (for now), firefox works (since the 'more-troubled' mac is my primary machine). thanks again for the detailed help!