Installed NPM 10.5 in eval mode on a server already running SAM 6.1.1.
Herein lies the problem. According to support (and "Compatibility of SolarWinds Orion Products for Installation and Upgrade" KB), these two aren't compatible when installed on the same system or using the same database. NPM versions compatible with SAM 6.1.1 are 10.7 and 11. 10.5 is "unsupported" and in my case, some parts of it don't work.
Moreover, there is no way to downgrade SAM from 6.1.1 to 5.5, bring it to compatibility with NPM 10.5, short of having a pre-upgrade database backup and thus losing post-upgrade changes and stats; in our case - 3 months worth of them.
Question: why doesn't the (NPM 10.5) installer warn that it found an existing installation of another SW product (SAM 6.1.1) and that it's not compatible with it?