Linux on ARMv8 emulation under Foundation Platform doesn't work

We are building our software for multiple platforms and one of them is Linux on ARMv8 (cross-compiled on Ubuntu 16.04). We have a test system (also Ubuntu 16.04) on which we run the Foundation Platform (FP). We invoke the FP and it launches the emulated Linux on ARMv8 system. It also launches a telnet terminal through which we can access the running emulation. We can also open an SSH session to the emulated system (ES). Through either, we can exchange files and launch test programs on the ES.

Command line goes like this:

Foundation_Platformpkg/models/Linux64_GCC-4.1/Foundation_Platform --image ~/linaro/img-foundation.axf --block-device ~/linaro/vexpress64-openembedded_lamp-armv8-gcc-4.9_20150123-708.img --network=nat --network-nat-ports=2222=22

where both the ELF image img-foundation.axf and the persistent image vexpress64-openembedded_lamp-armv8-gcc-4.9_20150123-708.img come from here: releases.linaro.org/.../.

We have run the FP in this way for a number of years (6 or 7?), but for some reason that we have failed to uncover, it stopped working sometime after June 2022. Something has changed, so we currently cannot access the ES anymore. When the emulation is launched, we receive the right signals that it is running, but the telnet terminal does not return control to the user, i.e., doesn't accept user input. So we have lost any access to the ES, can't exchange files or run programs. The telnet terminal, however, still seems to be connected to the ES. Here's its output:

The only input that the terminal accepts in this state is the escape character (Ctrl+]), which reverts it to the telnet prompt.

Similar behaviour is observed when trying to connect to the ES through SSH: nothing indicates that the connection failed, but the control is never returned to the user.

The CLCD window also does not display any GUI:

We have also tried the latest version of the Foundation Platform, with the same results.

Has anyone come across some similar scenario? Does anyone understand what's going on? Please help. We are not power users, we are just trying to test our software in a generic way, on a platform that we don't know very much about and for which we don't have and never had any hardware.