Stop using Save As and just Save. If LR is set to send images as TIFFs to PS all you have to do is use the Save command. I suspect LR is seeing the original TIFF without any adjustments and your Save As adjusted copy is not being imported back into LR.
Thanks Shootisbond007. I tried just using save and the TIFF goes back to LR like it did before, but it doesn't retain the aspect ratio change.
The View > Pixel Aspect Ratio in photoshop is for viewing only and not saved to the actual file, I guess.
Gotta use Image > Image Size with a non-constrained change, e.g. height * 0.75 for a 1.33 anamorphic shot.
Anyway, feel free to support the feature request for Lightroom here, so we anamorphic shooters could lose that need for Ps roundtripping only to fix the aspect ratio... 2016 oh my.. ^^