WG of Posn and Size fails on SubForm

[mkromberg]

Select DemoTabs. Notice in the logs:

{"WG":{"ID":"F1.TC.SF1","Properties":["Posn","Size"],"WGID":"38"}}
{"WG":{"ID":"F1.TC.SF1","Properties":{},"WGID":"38"}}
*** eWG of Posn and Size of F1.TC.SF1 failed ***

The client is returning a WG message, but it does not contain Posn or Size.