I have this issue on both an Eos Ti console and in Nomad, both running version 3.3.5 build 69. Under certain conditions that I can't quite pinpoint, I'm unable to lock frames in the displays.
On the Ti, the frame in question is Monitor 1, workspace 2. Tabs in that frame include 3.2 Live Magic Sheet, 2.3 PSD, 41.2 Video Stream, 14 Magic Sheets, 18 Macro Editor, 99 Diagnostics, 100 Manual, and 5 ML controls. No matter which tab is selected, I cannot lock the frame.
On the Nomad PC, I cannot lock the frame on Monitor 1, workspace 1. Tabs in that frame are 1 Live Table, 2 PSD, 12 Patch, 19 Snapshots, 15 Submasters, 36 Fader Config, 9 Pixel Maps, and 18 Macro Editor. Again, no matter which tab is selected, I cannot lock that frame.
The Lock Frame option is not grayed out on either frame, on either device. Has anyone else run into this? Am I missing something simple? Have I found a bug?