Selected Lines drop selection when changing from Select tool to Push/Pull tool

The description says it all.
Running on Chrome on Linux Mint.

Push/Pull doesn’t work on edges. It works on faces. Have edges selected makes no sense in terms of the operation of Push/Pull.

Could be a graphics driver problem. Are you up-to-date?

By “drop” do you mean they cease to be selected? If so, as @DaveR pointed out, this would be expected behavior. Push/Pull only works on surfaces, do selected lines would be discarded when starting Push/Pull.