It happens when people think that "2:1" in metric units is the right proportion.
"2:1" actually refers to pounds and pints.
For metric units, it is 60:40 (sugar:water) … really!
Last year I was mis-sold a small quantity of stuff "just like Ambrosia". It set. Not like Ambrosia.
First thing though is - do your bees need feeding?
Check and see (and feel the weight) before assuming they "need" feeding.
IF you conclude that feeding is still necessary, I'd remove (dump even) some/most/all of the crystallised stuff. Sugar is cheap, and I'll bet you had to damn near boil it to get it all to dissolve - risking HMF formation.
....
To avoid the risk of HMF formation when making up 2:1 syrup use warm water only. I use 450/500ml of cold water adding to this 200ml of just off the boil water from the kettle. Add this to 1kg of white sugar in a 2litre PET bottle. Put the cap on and shake thoroughly then shake again a bit later, repeating until the sugar has all dissolved. Leave to stand and use the next day, adding some Hivemakers recipe if desired. I keep a dry funnel to pour the sugar into the PET bottle and a cheap graduated cooks kitchen jug for the water.
Works for me