Launching "Activities" menu, then typing => disables smart card reader

[Louis Wust <louiswust fastmail fm>]

Greetings,

I have a very unusual problem. Consider this scenario:

1) Setting the scene: logged into GNOME on my work computer, which uses
   Centrify Infrastructure Services for Active Directory integration,
   with my work-issued smart card plugged into the embedded smart card
   reader in my Dell KB813t keyboard
2) Drive my mouse to the upper-left corner of the screen, which brings
   up the GNOME 3 "Activities" menu
3) Begin typing any sequence of characters on my KB813t keyboard
4) Immediately after typing the first character, the smart card reader
   begins flashing its activity LED
5) After a few seconds, the activity LED turns off completely
6) Due to a security policy setting at work, my screen immediately
   *locks* as a result of my smart card having been "removed"
7) Using the "sctool" command confirms that, indeed, my smart card is
   no longer seen by the system, despite it not having physically moved
8) The condition persists until I remove and reinsert the smart card,
   at which point I am able to unlock the screen using it + my PIN

Honestly, I don't have any idea where the problem occurs in this stack.
It could be a problem with GNOME, or with the kernel (& USB drivers)
provided by our distribution (Red Hat Enterprise Linux 7.5), or with
Centrify, or with the keyboard itself... What I can say is that the
procedure above is (close to?) 100% reproducible. I am asking for help
from this list because I can get the problem to recur *only* when using
the GNOME Activities menu, although I can't rule out the possibility
that it happens under different circumstances too.

I do have a USB traffic capture (with Wireshark + usbcap) which might
shed further light on the problem, but I haven't found the time to
decipher it yet...

Thanks for any assistance,
Louis