vino does not receive Shift+Function key events correctly

If I connect to vino (using UltraVNC client from Windows), any Shift+Function key press is received as the plain function key (no shift). This breaks my application which uses separate actions for F12 vs Shift+F12.

I experimented with xev, and it prints a KeyRelease event for the shift key before the KeyPress for the function key.

All function keys F1 through F12 are affected.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: vino 3.8.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-137.163~14.04.1-generic 4.4.144
Uname: Linux 4.4.0-137-generic x86_64
NonfreeKernelModules: mtxservmanager mtxmemmanager
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Mar 19 14:45:58 2020
ExecutablePath: /usr/lib/vino/vino-server
InstallationDate: Installed on 2016-01-11 (1528 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/tcsh
SourcePackage: vino
UpgradeStatus: No upgrade log present (probably fresh install)