Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.86
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
After using Ctrl-H or 1,2,3 (etc) to isolate a collection, Alt-H will only unhide objects from within that collection unless the cursor is hovering over the outliner.
Exact steps for others to reproduce the error
Have objects in several collections. Use Ctrl-H or press 1,2,3 (etc) to isolate to 1. From fullscreen Ctrl-H there is no way to unhide these collections.
Alt-H will only unhide all collections if the cursor is hovering over the outliner.
If you have 3 collections, and press 1, you will hide everything from collections 2 and 3. In fullscreen you must now press Shift-2 and Shift-3 to unhide these collections (if there are hidden objects in a collection you can unhide them using Alt-H provided the collection itself is already unhidden).
This behavior is actually GOOD for some, based on what I've read. The frustration is that there is no hotkey to unhide collections from within the 3D Viewport.
Ideal fix: Leave the behavior as is so that Alt-H only works on selected collections (to allow for a more selective unhide). Add a DISTINCT hotkey to "unhide all collections".