Incorrect indentation with simple macros

In one of my source files, suddenly Creator wants to indent everything by 6 indents (24 spaces). This happens at any location in the source file beyond a certain point.

I managed to create the following minimal example (which I cannot reduce further):

#define GGG(ARG) void g() { }

GGG(ARG)

inline int operator >> (int, int) { }

#define FFF void f() {}

FFF

Put this in a .h file, save it, move the cursor right after FFF and press enter. Creator will indent everything by 6 indents.

Please ignore whether the code makes sense, it's just a minimal example. The actual code compiles fine and uses simple macros with arguments to avoid repetitive typing when interfacing with a C library.