Similar as for the GoldSync Service we absolutely do not recommend in the context of GMWEB to use mapped drives. It is also not a recommendation from Microsoft for IIS. The main problem is the AppPoolidentiy user to access the mapped drive which usually is not available and may require additional tweaks and configuration. for example mapping the drive persistent for the used windows account. It is absolutely recommended to work instead with UNC paths only.
For more information, please contact Wizard Systems Support dept.