did you follow the docs here: Steam DRM (Steamworks Documentation)
i use that
builder\steamcmd.exe +login mysteamaccount mysteampassword +drm_wrap 480 "D:\src\steamworkssdk\steamworksexample\release\steamworksexample.exe" "D:\src\steamworkssdk\tools\ContentBuilder\content\windows_content\SteamworksExample.exe" drmtoolp 0 +run_app_build ..\scripts\app_build_480.vdf +quit
and this seems to work for me - again the issue only happened for me for about a week… and it happened like several months ago for me. another thing you can try is updating 4.20
try making a batch file and running it - automating it with this steamcmd.exe from steamworks 1.42 which you can get from here Steamworks SDK (Steamworks Documentation)