The QMC user may not have the proper access rights and/or licences/configurations to perform the task. To exclude some of the potential issues do it again with the desktop client on the server-machine with the services users.
Tried the service user approach, same scenario - QV desktop work and QV server reload, for QV server we found EXCEL.exe stuck in process and unable to close.
Very likely is there any popup within the Excel asking to login or for configurations like the default file-format or any other stuff which gets no respond and/or the execution of macros is restricted and/or linked content couldn't be resolved or ... a lot of possibilities. One way to exclude many of them would be to perform the entire Excel stuff manually - again on the server machine and with services user. Further within the Excel macro you should set the visibility and the responds of any kind of errors/messages to true to see what happens and where it may break.
