If this helps... this does not happen with 18.04.3 LTS
LSB Release: No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 18.04.3 LTS Release: 18.04 Codename: bionic
gnome-screenshot version: gnome-screenshot 3.25.0
uname -a: Linux hostname 4.15.0-74-generic #84-Ubuntu SMP Thu Dec 19 08:06:28 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
If this helps... this does not happen with 18.04.3 LTS
LSB Release:
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.3 LTS
Release: 18.04
Codename: bionic
gnome-screenshot version:
gnome-screenshot 3.25.0
uname -a:
Linux hostname 4.15.0-74-generic #84-Ubuntu SMP Thu Dec 19 08:06:28 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux