There have been several problems encountered with the latest release (1.8.0) version of the Affinity applications.
Because of this, the team has released various 1.8.x beta versions with bug fixes in them.
I think (but I could be wrong) that the current recommendation is to use the latest 1.8.x beta until the next 'proper' release version.
The betas can be found in the relevant forum area (depends on which OS you have).