Stunted flowers on clematis montana?

[Catabogus]

I have a large clematis Montana which has flowered beautifully in previous years. However this year the flowers are sparser than usual, and - the strangest thing - they’re only about a quarter to a third of the usual size!

Is there a reason why they would be so stunted? I’ve googled but can only find clematises which don’t flower at all, not ones with tiny flowers.

The unusually cold spring, maybe?

Mine isn’t loving life this year either, similar symptoms.

Everything is stunted this year. Horribly cold and dry April, then cold and wet/windy May.

Mine is the same and so are all my flowers, it was the hard snow and frost we had earlier in the year I think x