SaveRAM from Mupen64Plus-Next core is incompatible with BizHawk seemingly

Summary

I'm not an expert on this, but typically when transferring a saveram file from a libretro core that is the same or a forked version of said emulator in BizHawk results in it being able to load it assuming you change the file extension from '.srm' to '.SaveRAM'. However, for whatever reason the Mupen64Plus BizHawk core appears to ignore the file contents and make a new, empty savegame instead. I haven't tested this extensively, but it appears to affect Ocarina of Time, as well as Majora's Mask.

While I understand that there may be differences in how each of these versions of Mupen64Plus store and read saves, I've had success with importing various bsnes saves into BizHawk without a hitch. If this isn't something anyone intends to fix, I'd appreciate a better understanding of what's going on here as well as to know if there is a potential workaround.

Repro

1. Download and run Retroarch 1.10.0. The system architecture shouldn't matter as core saverams are identical.
2. Use the built in core updater to acquire the Mupen64Plus-Next core.
3. Load content and select either Ocarina of Time or Majora's Mask, both should work for this example.
4. Create a savegame, make note of the name you selected.
5. Close out of Retroarch and navigate to the 'saves' subdirectory. There should now be a .srm file with the rom's original filename.
6. Copy this .srm file into Bizhawk's N64 SaveRAM folder, then change the file extension from '.srm' to '.SaveRAM'.
7. Load Ocarina of Time or Majora's Mask in Bizhawk depending on the associated saveram file.
8. When in the file selection screen, the savegames you created earlier are not present, effectively making your efforts wasted.

Host env.

• BizHawk 2.7.0; Windows 11 Pro 22000.469 OS; AMD Ryzen 7 5800X CPU; NVIDIA GeForce RTX 3070 Ti GPU

Start by reproducing the issue with RetroArch 1.10.0's Mupen64Plus-Next core and BizHawk 2.7.0, using the Ocarina of Time or Majora's Mask steps described above. Compare how the .srm and .SaveRAM files are handled; done means an imported RetroArch save appears in BizHawk's file-selection screen or the incompatibility and workaround are documented.