"Maximize Compatibility" TIFF broken?

When using "Maximize Compatibility" for an HDR developped image, outputing to 16-bit or 32-bit TIFF with Rec P2020 color space, the image is not displayed in HDR by the Gain Map Demo App.  Furthermore, when roundtripping through other apps (e.g., PtGui), the resulting image is not even recognized as HDR by Lightroom?  When not using "maximize compatibility", everything works as expected (displayed as HDR by Gain Map Demo, roundtripping works).

Is this behavior expected?  If yes, then I don't know what "maximize compatibility" is for - it really just breaks things?