Incremental deployment does not work if the target directory is cleared. For certain folders this automatically happens on reboot, in particular /tmp.

If incremental deployment is turned on (default) then nothing will work if the target folder is cleared between deployments.
Reason: Qt Creator does not seem to check this and assumes all/most files are already properly deployed.

Workaround: turn off incremental deployment at least once after clearing the target directory.
This should at least be mentioned in some known issues list.