Safari 16.6

Safari 16.6 for Monterey and Big Sur was actually re-released on the 26th with a bump in build numbers:
Monterey Safari 16.6 (17615.3.12.11.3)
Big Sur Safari 16.6 (16615.3.12.11.3)

To this day, I still cannot use Safari (on Mac, but OK in iOS, go figure) to display any map or infographic on my city, state highway dept. or utility’s websites.

But other browsers work fine? Can you post some links?

Chuck, I had a very similar problem on my MacBook Air (2020) that somehow migrated to my MBP 2022. I think the problem was on my 2011 MBP initially but cannot remember that far back.

Frustrating. I realized that the culprit managed its way onto the new machine when I moved data from the Air to the Pro via a Carbon Copy Cloner restore.

Since there is really no easy and though way to reformat an SSD so that one knows there is not a thread of anything old left on it, I asked my Apple dealer to do it. It took a lot of convincing that I wanted a better than VIRGIN MBP. They did as I asked. Then, using an external Toshiba T5 SSD, I moved only the data files I needed from the SSD to the MBP.

I then downloaded absolutely fresh copies of the programs I needed from the net. I chose this order so that the freshly downloaded apps were initially opened using that data file I had just placed on the drive. I did NOT want the app to create a new file. (The drag and drop feature works quite well here.O

I copied no files from the ~Library ƒ. I even rebuilt my Little Snitch database from scratch instead of loading my saved prefs file.

The problem was fixed. I cannot promise nor guarantee that my solution would work for you. If you have the time, and a number of faithfully executed backups, It just might be the ticket out of your thicket. If you do take me up, I really would like to know the outcome.

I just want to reiterate that ONLY data files that one must need gets copied to the newly completely erased internal drive that has a pristine Mac operating system installed via the restore option menu. I needed to have religion, patience, and more patience but I did kick my problem to the curb. I sure am hoping that I never have to do that again!

I discussed clean installs in this general area in:

It’s definitely worth trying a lot of other solutions first, since these deep rebuilds take a ton of time.

example:
Michigan DOT Traffic and road conditions map.

Overlays and legends show, but not map layer (blank white screen).
Displays correctly on Firefox, Chrome, Duck browser, Safari (on iOS/iPad OS).
This and other data maps (electric utility outages, etc.) and info graphics are never displayed on Mac Safari. Sometimes get a “OpenGL or WebGL Not Supported” back from sites. Currently MBPro (2016), Safari v 16.6, Monterey 12.6.8.

I tried it on my Mac (Mac mini 2018, macOS Big Sur 11.7.9, Safari 16.6 (16615.3.12.11.3, 16615)).

It all seems to load normally. The map layer loaded a few seconds after everything else, but it all loaded for me.

My only Safari extensions are AdBlock Plus, the ABP control panel, and Webex (disabled). ABP was enabled, but didn’t seem to affect the site’s behavior.

My ISP is Comcast. I am using my own DNS server (on a Raspberry Pi) that resolves everything on its own (via the root-servers, not falling back to any third-party DNS server).

It works here in macOS 13.5 Ventura too.

Have you tried it from a guest account to see if there might be an account-related setting that’s causing it? And do you have another Mac that could try it (or do you have a friend who could bring a laptop over)?

It feels like something highly specific to your setup, and some of these troubleshooting steps might reveal where to look.