This is a regression caused by Bug 5241. The new Xserver does not correctly handle my "Gold" mouse cursor theme, in conjunction with the Xfixes extension. I have an animated cursor theme where the cursor animates only every ~8 seconds or so. In this case, XFixesGetCursorImage will return a 1x1 invisible cursor until 8 seconds has passed. This worked correctly with Xorg server 1.14.
Upstream bug report: