Desktop viewer disappears at logon,Restart Citrix ICA service solve the issue
 

Workaround
Remote to problematic vm
cd C:\xxxxx\PSTools
psexec.exe \\IP address of VM -u Domain\username -p Password /s cmd
Restart Citrix ICA service
net stop porticaservice /y
net start porticaservice

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Problem Cause

session is not disconnected properly

Line 10660: 10643,3,2017/08/10 17:57:08:43006,7164,3616,-1,ICA Service,_#dotNet#_,0,,7,CDF_NET_ENTRY,"Citrix.Portica.StackManager.ProcessAcceptConnection",""
    Line 10669: 10652,3,2017/08/10 17:57:08:43017,7164,3616,-1,ICA Service,_#dotNet#_,0,,3,CDF_NET_INFO,"Citrix.Portica.StackManager.ProcessAcceptConnection Found already existing IcaSession object (expected)",""
    Line 11740: 11723,2,2017/08/10 17:57:08:88543,7164,3616,-1,ICA Service,_#dotNet#_,0,,3,CDF_NET_INFO,"Citrix.Portica.StackManager.ProcessAcceptConnection SessionAlreadyEstablished with MainConnection: True ACR enabled: False",""
    Line 12191: 12174,2,2017/08/10 17:57:08:97444,7164,3616,-1,ICA Service,_#dotNet#_,0,,4,CDF_NET_INFO,"Citrix.Portica.StackManager.ProcessAcceptConnection Stack ConnectionAcceptComplete succeeded with existing session (connection already established) => incoming connection will be closed",""
    Line 12192: 12175,2,2017/08/10 17:57:08:97445,7164,3616,-1,ICA Service,_#dotNet#_,0,,3,CDF_NET_INFO,"Citrix.Portica.StackManager.ProcessAcceptConnection Found existing session (connection already established) => closing second incoming/pending connection",""
    Line 12745: 12728,1,2017/08/10 17:57:10:01628,7164,3616,-1,ICA Service,_#dotNet#_,0,,7,CDF_NET_ENTRY,"Citrix.Portica.StackManager.ProcessAcceptConnection Result: False",""
CPE Analysis
PICAStackConnectionClose() function is getting executed. This function is used to close down a connection by closing the endpoint.
TOK_TERMINATE errors coming from the traces which signifies that the client has sent a network packet to terminate the session.