Tablo DVR has blank thumbnail frames during fast forward

We have two Roku 3 units, and since the Roku 12 OS update was installed, we are no longer able to use the thumbnail frames to fast forward through commercials on our Tablo DVR recordings, because they are blank for the most part. We sometimes will see a picture on one out of every 5-10 frames, but frequently none. If we use a PC or Android phone app the thumbnail frames work fine, and also on a TCL Roku TV we have in an office area, but not on the standalone Roku 3's that are used on our main TV's.

Has anyone else had this issue, and if so, have you found a fix??

Thanks!

DP