I am having the same issue since allowing my new laptop (which I literally booted up for the first time on Sunday) to update today. In the Optional Features list (capture below) there is no MS Media Pack available to install - I checked using an elevated
PowerShell and there's nothing there for it either. I've got Windows Media Player (it's right there in my Installed Optional Features) and I went and downloaded and installed a punch of extras from the MS store, too, like HEIF Media Extensions and VP9 Video
Extensions, just to see if any of that would do something. Nope.
So then I tried rolling back the updates from this morning, and got error messages refusing to uninstall two of them. Then I tried installing the most recent Media pack that is available for download (1903) and it told me that it wasn't compatible for my system.
Now I'm stuck.

This is infuriating because I cannot play Netflix, am tormented by blinking gifs that start to load and then freeze, then disappear, then repeat, all over social media, and have an extremely annoying error message bar that tells me I need to install the
media pack jumping up under my toolbar on my browser constantly *just to remind me* that I don't have access to this damn thing.
Is there any chance at all MS will just give us a link for this? It's an easy fix, for heaven's sake!