We also experienced this issue with an QT application. We could track it down to the by default disabled BIG-REQUESTS extension in version 22.214.171.124.
Commenting the line
X2GO_NXAGENT_DEFAULT_OPTIONS+=" -extension BIG-REQUESTS"
in x2goagent.options resolved this issue for us.
Note, that this applies only for new sessions.
Best regards, Jahn