Boot Device Not Found, but SSD recognized?

Running Windows 10 Home v.22H2 on an 11th-gen i7, using the Western Digital SN730 SDBPNTY-512G SSD that came with the prebuilt computer (which has otherwise been working smoothly since I got it last March).

I first got the boot device error on Wednesday morning—went into BIOS, everything looked fine, exited, and for some reason it booted up again with no problems. No more issues for a day and a half—then Thursday evening, I get the boot device error again. This time I end up having to get in through the startup repair menu, as suggested here. Now, when I restart the computer, I have to do it through startup repair every time.

The thing that’s confusing me is: sometimes, when I boot into BIOS, the SSD isn’t recognized. That’s totally expected for this issue—what’s weird is that after booting through startup repair, both diagnostics and the Western Digital dashboard recognize the SSD as existing, up-to-date in terms of firmware (version: 11140000—so this situation doesn’t hold), and otherwise healthy. And sometimes the SSD does show up in BIOS, but still isn’t recognized as a boot device?

Any ideas what might be causing this? I updated from BIOS 3.07 to 3.10 after the second boot device error, but didn’t see any threads suggesting that it would wipe the devices or anything… and that wouldn’t explain the first two errors in the first place! Haven’t tried booting from an external device yet, just confused about what’s up with the SSD.

@Matt_Hartley that is something like I’ve experrienced here. Please take a look once you’re back!

Update: this morning, computer booted normally again? I am now thoroughly confused, but will update again if/when the boot device error comes back.

More updates: starting about a month and a half ago, this problem started to reoccur with increasing frequency; apparently some files got corrupted along the way, and I had to reinstall Windows from a USB. From there, problem largely solved for the past two weeks, when I got the boot device error again—this time with my SSD not recognized (so could not reinstall from disk). Prior to this most recent failure, the Western Digital dashboard had reported that the SSD’s health was at 98%.

Potentially relevant note: even during the periods with no major issues, the PC would crash if closed while still running (including while asleep). Rebooting usually fixed it, but I wonder if it’s symptomatic of the bigger issue…

Does anyone have any suggestions for how I might check whether the issue is the SSD or some other hardware problem? (Asking largely because all of the hardware diagnostics I ran said the SSD was fine… but only, of course, when the computer was working to begin with!) I’m fine buying a new SSD if I have to, but would obviously prefer not to drop the cash if it won’t actually solve the problem.