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LT1054 Voltage Inverter fails to start up with no load


I'm using LT1054 to produce -12V from +12V using the "Basic Voltage Inverter" circuit from "Typical Applications" on the data sheet.

I have disconnected the load from the -12V output from the LT1054.

The issue I have is that the LT1054 fails to start up properly when 12V is applied.

The OSC pin produces an irregular waveform, not the expected sawtooth. The VREF pun does not produce a stable output. VOUT is not stable and is about -4V on average.

However, if I momentarily touch FB/SHDN with a DMM probe, the device switches to normal operation. The output is -12V, OSC produces a sawtooth and VREF is stable.

There is a warning in the data sheet about allowing VOUT to drift positive due to a positive supply referenced load. However, at no time does VOUT go positive.

Can anybody help me understand this issue, please?