Sharp Aquos LCD TV "forgets" display Underscan setting after Mac mini sleeps

I have a brand new Mac mini (Late 2014 model) connected to a 60" Sharp Aquos LCD TV via HDMI cable, a configuration I used without issue for several years with my previous Mac mini, and which has worked for the new one for the two weeks I've had it as well. That is, it did until I upgraded to macOS High Sierra 10.13.1 yesterday. 😢 After the install completed, the resolution was maxed out and the text was too tiny to read, so I went into System Preferences to fiddle with the Display settings and landed on this configuration:

I had to use Underscan (which I don't recall ever having to do before) to shrink the display to the proper scale in order for everything to be visible on the screen, and it looks just fine on the Aquos with the settings shown. I soon discovered, though, that after the computer goes to sleep and I wake it back up, the display is "enlarged" again -- as if no Underscan setting were in effect. To be clear, the slider has not been reset to Off: It's still in the same position as shown above, but the display has reverted to the maximum scale (with things like the Apple menu no longer visible on the physical screen) as though Underscan were turned back down to zero. Clicking the slider at its current position causes the display to immediately snap back to the desired, scaled down/underscanned size. Fwiw, the problem also manifests if the Default resolution (1080p) is selected, as well as any of the other Scaled resolutions.

I discussed this on the phone yesterday with Apple Support, and while the rep did understand the issue as I described it, we were unable to adequately troubleshoot and diagnose it via screen sharing because 1) he lost his screen share connection every time I put my Mac to sleep to try to demonstrate the problem; and 2) even while viewing my screen, he could not see the effects of me changing the Underscan setting in real time (presumably because it only applies to/affects the local device/monitor on my end). Ultimately, beyond asking me to swap out the HDMI cable (which I did to no end but to humor him), he was only able to offer a guess that it was a problem with the TV not recognizing the Underscan setting after the computer returns from sleep mode, and suggested trying a different monitor to confirm or disprove that theory. But, I don't have ready access to another monitor, and it seems suspicious that this only began after installing the latest macOS version. To that, he said I could try reinstalling the OS, which I hesitate to do if I can avoid it.

Do you have any experience with the issue of the Underscan setting seemingly being "forgotten" after your computer sleeps (either before or after installing 10.13.1) and know how to resolve it, or have other suggestions for Display settings to use with this particular Mac and monitor for better results? For now, I am having to go click the Underscan slider to correct the display every time I wake my mini. 😟