Continuing the "circling cruise missiles" theme.
DCS Steam version 2.8 had no problems, but automatically upgraded to 2.9, GLSDB, ATACMS, PrSM, and all cruise missiles from CH mods stopped following the set trajectory. The cruise missiles that were added to the game by the developers flew where they should.
How did I solve this problem?
Since I am playing the DCS Steam version, I went into the game settings in the Steam app - properties - Beta versions - Beta testing, and from the drop down list I selected "openbeta". By updating to it, the missile issues went away.
Hope it helps someone)