A bug when using the 'Create do something' option on the palette of blocks Functions

I use the ‘Create do something’ option:

  1. I select it. The ‘do something’ block appears. Separately, it can not be dragged into the field.
  2. I click once on the ‘do something’ block and then it will be added to the editor at the same time as the ‘to do something’ block. If you do not click, then when you select ‘to do something’ the ‘do something’ block will not be added.

With Variables and Control blocks this works differently:

I select option ‘Create do something’. A new block appears, but to drag it into the working field, you need to drag the variable block for which the context menu was called.

Is this how it should work?

But in some cases a bug is shown below (Firefox).

Found one of the reasons. If you right-click on a block in the palette and then press Del, then this block will no longer be selectable and it will appear when you open other block categories.