Probably connected to T8038: NSIS: Updating line omitted if browser integration is installed
On reinstall, preselection of the installed components only works, if the browser integration component is installed. Otherwise the default set of components (all but browser integration) is used.
I understood that this is done on purpose, i.e. all other components are explicitly always preselected.
Without browser integrations installed, the preselection works fine though.
Probably this happens, because the info in the registry is missing as soon as browser integration is installed, see T8038: NSIS: Updating line omitted if browser integration is installed
Oh, surpisingly it's the other way around: if the information is given in the registry key, all components are preselected. If the key is missing (browser integration installed), only the installed components are preselected. I wonder where the information of the previously installed components comes from, if not from the MementoSection_SEC_kleopatra fields.
Fixed. The problem was that the selected sections were stored in the 64-bit registry (unless browser integration was installed; see T8038), but they were read from the 32-bit registry.