Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 418.81
Broken: version: 2.80 (sub 50), branch: master, commit date: 2019-03-18 20:40, hash: rBce09b93955de
Subdivide the entire hair does not cause the problem, the highlight appear at the correct place.
Short description of error
In Particle edit mode, subdivide a segment of the hair will cause the selection highlight appear at the wrong part.
Exact steps for others to reproduce the error
With the default cube, add a hair system, reduce the number to 1, switch to particle edit mode, select 2 connecting vertices, then subdivide.
Now if you select an individual vertex, the highlight appear at the wrong place