It appears a bug has been introduced with the latest patched installer version 2.0.5-1. Once there is an installation, subsequent runs of the maintenance tool crash immediately after the meta data has been downloaded. Error messages are brief:
On Windows: Fatal: Exception thrown: Unknown exception
On Linux: std::exception
Errors started following maintenance tool update which had everything grayed out except for the maintenance tool itself. Subsequent runs resulted in the exception.
I deleted everything on Windows and started from clean and it worked until I put the laptop to sleep and tried to resume the download and install at home. (I had to kill the installer and start again though).
It could plausibly be only related to the Qt Automotive Suite repository - I expect someone closer to knowing the implementation would be a better judge of whether this is the case.