NHibernate 5.5.1 is now released.
For a list of resolved issues & pull requests, see the milestone or the release notes.
Binaries are available on NuGet and SourceForge:
https://sourceforge.net/projects/nhibernate/files/NHibernate/5.5.1/
https://www.nuget.org/packages/NHibernate/5.5.1
3 issues were resolved in this release.