Prunus Padus (bird cherry) -- no leaves :-(

Hi -- my mature (at least 18 years old) Prunus Padus has buds but they have not opened into leaves as I would have expected by now (3 May 2023). Last year in the drought the tree dropped all its leaves early after a normal flowering and growing season. This year it has formed leaf buds and the branches and twigs are flexible and appear to have sap flowing and there is no obvious sign of any disease but so far no leaves -- any advice would be most welcome

 

Just wait a bit and see what happens, but it doesn't sound good.