If you can run my schematic without .option fastmath=0, check Edit > Preferences to see if fast math is already disabled. If I force .option fastmath=1, the schematic I uploaded still returns a timestep is too small.
Your schematic can run with Qspice80.exe too.
Well, your symbol also built correctly. However, when you import the .subckt, you didn’t select Include Entire File option ( MOV subcircuit component check (PBKAC) - QSPICE - Qorvo Tech Forum), and all dependent subcircuit not included, that why you still need .lib to link the library file.