Golden Coconut bug?

[The cross-dressing nightmare]

Hi folks, I paid the Joja Parrot on Ginger Island to collect the remaining golden walnuts - I was 35-40 walnuts short when doing so. Since doing that, I haven't been able to get the Fossilized Skull (my last remaining fossil needed for the Field Tent Museum) from a Golden Coconut at Clints. I've opened almost 100 golden coconuts at this stage, but I suspect that it may not be being triggered because I've technically "completed" Ginger island - but I can't get access to the Ostrich Incubator without it.

Am I just having the worst run of luck, or has anyone else had this issue? TIA