Artifact used (ex. androidx.appcompat:appcompat:1.0.0-alpha1): androidx.recyclerview:recyclerview-selection:1.1.0-rc01
Version used: 1.1.0-rc01
Theme used: Theme.AppCompat.Light.DarkActionBar
Devices/Android versions reproduced on: Motorola Moto G6, Android 9

When the item views of a RecyclerView have OnClickListeners attached, the behaviour of firing onClick events during selection is quite unpredictable. As soon as at least one item was selected, classic ListView did no longer fire any click events for individual list items until all items were unselected.
Current recyclerview-selection exhibits two behaviours I would consider a bug, but maybe I'm using the API in a wrong way:
1. When long-clicking an item to enable multi-item selection, the item is marked as selected/activated as expected. But as soon as you release the finger, an onClick event will be triggered, despite the fact that RecyclerView is currently in selection mode. This behaviour is new since 1.1.0-rc01 and was not present in 1.0.0.
2. After enabling selection mode by long-clicking an item, you can select/activate other items by simply clicking on them. This works fine as long as you click through the items slowly. Then one by one gets selected and no onClick events get fired. But when you click a bit faster, every second item is not selected, but instead clicked (triggering onClick event). This problem existed in 1.0.0 and is still present in 1.1.0-rc01.

The following log shows a sequence of onItemStateChanged and onClick events triggered by long-clicking item 0 to enable selection, then clicking items 1, 2 and 3 quickly.
Expected result: Item 0 is selected, then items 1, 2 and 3 are selected, no onClicks get triggered.
Result on my device: Item 0 is selected, then onClick is triggered for item 0. Items 1 and 3 are selected and item 2 fires an onClick event in between.

click item 0 and hold button:
2020-07-13 21:55:01.402 15005-15005/com.example.recyclerviewdemo E/onItemStateChanged: 0: true
item 0 is selected, now release finger:
2020-07-13 21:55:02.306 15005-15005/com.example.recyclerviewdemo E/onClick: item 0
now click (and release) items 1, 2 and 3 quickly:
2020-07-13 21:55:06.850 15005-15005/com.example.recyclerviewdemo E/onItemStateChanged: 1: true
2020-07-13 21:55:07.038 15005-15005/com.example.recyclerviewdemo E/onClick: item 2
2020-07-13 21:55:07.236 15005-15005/com.example.recyclerviewdemo E/onItemStateChanged: 3: true

Attached is an Android Studio project to reproduce the behaviour.
Item IDs == item positions for brevity, the library behaves the same way in a more complex project with "real" item IDs and a custom key provider.