"refactoring" only works once when using clangd

i've been seeing a funny issue with qtc snapshot builds (e.g. 38b2bb9fb2fbc0d764605c9a103ff58ea26c2d61) with clangd support: the "refactoring" functionality (move to definition to source or clang-tidy refactorings) only seem to work once after restarting qtc. after the first successful refactoring, the "clang-tidy bulb" does not show refactoring hints and the "refactoring" context menu entry only lists "rename symbol under cursor"

the behaviour is back to normal when clangd is disabled