I can reproduce this on MacOS as well.
The problem seems to be if the window is too small after the folder is expanded, it won’t scroll down to the file on the first try.
If the main app window is big enough, this doesn’t occur.
Curiously, this only seems to happen on the first try. After it has occurred, I can’t seem to make it happen again. No amount of collapsing folders, navigating, etc will make it happen a 2nd time, for me, until I reopen the Help Vault.
(Also, it happens whether clicking on the UI buttons, or invoking the commands through the command palette.)