Manually compiled helix cannot highlight syntax cpp

[yangchaoFree]

According to the document, manually build helix:
git clone https://github.com/helix-editor/helix
cd helix
cargo install --path helix-term --locked
in helix dir, running hx, it was found that the cpp program cannot highlight syntax:
./target/release/hx test.cpp.

While download the release version (helix-25.07.1-x86_64-Linux) and after decompression, its hx program will normally highlight the cpp syntax.
But replacing the release hx with my manually compiled hx in the helix-25.07.1-x86_64-Linux directory. it still fails to highlight syntax.

[Rudxain]

Likely, you haven't set the runtime