Can't install submodules for older versions of ArduPilot repository

I’m having trouble installing submodules for older versions of ArduPilot repository. I need to run SITL for ArduCopter v3.6 and ArduPlane v4.0.6. Over the weekend the boot drive on my PC died and I need to finish some work using older versions of firmware. I didn’t have any problems building older versions of repo in the past. I do the checkout to a specific tag in repo but then submodule installation fails on libuavcan and some other submodule. To be honest I didn’t note it down but I can easily recreate it. I’ve tried installing submodules on a different PC running Ubuntu 20.04 with no success. I can however build the SITL on the latest version of ArduPilot repository. I wonder if someone experienced a similar issue. I don’t understand why the submodule installation fails when I’ve had no trouble with it in the past. I hope with some help I can work out this issue.