Hi,
That is unexpected behaviour. The ROM routine to load to a memory address should wait for tape input.
The only real hardware I had to test on was a 48k speccy, which was able to load and save fine. The code and save file data are the same in 128k mode and it worked via the Fuse emulator's tape emulation on all the 128k ROM versions. I think I recall other real hardware 128k user's being able to load from tape, so I'm fairly confident it should be working.
Could you try loading the game in 48k mode and see if you can load the save file data? Are you able to save and load other data with your tape drive (like a simple BASIC program)?
Sorry for the difficulties.