Descriptive Problem Summary:

This is a fresh install of Windows 11 Pro 24H2 on fully supported hardware.
I first installed Byond 515.1647 from the website, whereupon the pager refused to start producing error 0xc000007b (a fairly generic error indicating some dll dependency failure). I eventually fixed this by downloading d3dx9_43.dll separately and pasting it into the BYOND\bin\ folder (using old DirectX installers downloaded from Microsoft as has been suggested in other topics did not fix this).
After starting the pager and attempting to connect to a game, Dreamseeker crashes. There is no error message accompanying this, the only information is in the event viewer, ExceptionCode c0000005 (access violation) within byondcore.dll.

I have tried applying various compatibility and elevation settings to both byond.exe and dreamseeker.exe with no change in result.
The same exception code is produced in 515.1647, 515.1645 and beta 516.1656. I was previously on Win11 22H2 using 515.1645, though I do remember some issues getting it going when installing on that version, but this was well over a year ago and I don't remember the details of what I did.

I have also tried reinstalling and repairing the Visual C++ Redistributable package with no effect.

WinDbg provides the following detail:

(2ba0.24d0): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=ffffffff ebx=00000001 ecx=011fd568 edx=00cd0000 esi=011fd568 edi=003cb5c7
eip=5c160123 esp=011fc484 ebp=011fc490 iopl=0 nv up ei ng nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010286
byondcore!DMString::operator=+0x83:
5c160123 f00fc143fc lock xadd dword ptr [ebx-4],eax ds:002b:fffffffd=????????
0:000> g
(2ba0.24d0): Access violation - code c0000005 (!!! second chance !!!)
eax=ffffffff ebx=00000001 ecx=011fd568 edx=00cd0000 esi=011fd568 edi=003cb5c7
eip=5c160123 esp=011fc484 ebp=011fc490 iopl=0 nv up ei ng nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010286
byondcore!DMString::operator=+0x83:
5c160123 f00fc143fc lock xadd dword ptr [ebx-4],eax ds:002b:fffffffd=????????

Please let me know if anything else can be provided or if you want the entire WinDbg output. I suspect this is rooted in locale or encoding somewhere.