Hello, everyone!
First of all I’d like to apologize that this question is not about a game that I have created, but rather a game that I’m trying to play - Star Wars Jedi: Fallen Order, which uses Unreal Engine 4.21.2. Yes, I’m pretty desperate to come looking for help here. 
I looked for forum rules but could not find anything that would forbid this question.
That said, I’m a computer programmer by trade (not a game developer though), so at least I hope I’ll be able to provide plenty of details and feedback to keep this interesting. I’m hoping that someone with enough experience will be able to intuit the problem.
The symptoms are:
The game starts fine and I get to select the difficulty level and then start a new game. Then it stars to load the first (tutorial) level which… usually takes forever. Well, I’ve lost patience after 20 minutes, so maybe it would load after that but I doubt it.
Very few times however I’ve gotten lucky and the level has loaded, but… there were assets missing. NPCs mostly, but also some floating platforms - the lack of one of which prevents my progress.
In the opening cutscene there’s an NPC walking up to me to say something, and he’s invisible for the first part. His speach and subtitles do show up though. Then, just as I gain control of the characer, he suddenly appears for a while until I get to next area where he promptly becomes invisible again.
As I’m walking through the tutorial there’s supposed to be other NPCs on the sides, but they are completely missing - both models and audio.
But then there are two more baffling pieces to this puzzle:
First: If I edit the configuration file (or enable console with the Universal Unreal Engine 4 Unlocker and change the value there) and change sg.ShadowQuality=4 THEN everything starts to work. Well, at 1-2fps, which is absolutely unplayable, but the sounds visuals ARE there, complete. Loading also drops from infinity to about 2-3 minutes.
The low FPS is understandable because I have an old GPU - Radeon HD 7870, 2GB. It’s still within the minimum spec of the game though.
Changing the ShadowQuality back via console leaves the nearby NPCs in place, but if I travel onwards then the further NPCs/assets are missing again.
Second: if I come to a place where an asset is missing, then hit ESC to open up menu, wait a few seconds, and the go back, the missing content appears! At least until I walk around another corner where it hasn’t loaded yet and I get to repeat the whole song and dance.
These symptoms are so odd that I haven’t found anyone else on the internet who would have anything like it. I’ve been fighting this for a week and I’ve tried all the usual stuff: repairing game files, redownloading, trying slightly older GPU drivers, disabling everything I can disable on system startup (a “clean” boot), windowed/fullscreen, etc. Nothing has any effect.
Does anyone with UE4 experience have any intuition about what could be wrong here and what I might try to do to get the game playable?
Just in case, my full system specs. They are slightly lower than the official minimum, but should still be capable of running the game on lower settings:
CPU: AMD Pheom II X2 550
RAM: 12GB DDR3
GPU: Radeon HD 7870 2GB
SSD: 256GB Samsung 860 Evo
OS: Windows 10 Home.
Nothing is pirated or tweaked or overclocked.
Thank you very much for any help!