GMS 2 ini filehead ache

I have some code which has been working for ages and now does not seem to work at all.

I tried opening a new project from scratch to test the following code.

ini_write_real("test", "test", 6);
ini_read_real("test", "test", "");

This gives me the following problem.

ini_read_real argument 3 incorrect type (string) expecting a Number (YYGR)
at gml_Room_room0_Create (line 4) - ini_read_real("test", "test", "");

If I read it as a string it works.

I have no idea what is causing this. It started doing this overnight.
Ah OK I see. I'm very confused though because I had this code typed out this for ages and it's been working fine. Then since the update it started to complain. I thought the third part was the legacy bit which if left empty does not do anything.