APM Remote Desktop to Win Server 2012 R2 not honoring window size setting

A similar problem was mentioned in a q. from about 5 months ago ... but mine is a little different. I have an remote desktop link on a portal webtop that stubbornly opens at 800 x 600, no matter what I set the window size to. When I first checked it, the size was set to custom, 800 x 600. But changing it has no effect. I've made sure my portal session was cleared, change the portal virtual server to have no caching, emptied my browser cache/cookies (wasn't sure if that mattered), but no luck. I've changed the caption - just to be sure i was getting the new config for the RDP - and i do see the caption change - but the window stays at 800 x 600, even with 100%, 90%, fullscreen set. client is Win 7 Pro x64, IE10. Thoughts?

 

The other topic mentioned setting the Win Server 2012 to not have "NLA only" ... but that wasn't tried, the poster worked around it by setting up an app tunnel from mstsc. If necessary, we'll do that, but ... better if it just worked.

 

LTM 11.4.1 bld 608 running on a 2000s box.