If you perform Part->CheckGeometry with BOP Check
enabled you will see several errors in Fillet019. In this situation in almost all cases further boolean operations fail.
Further checking shows that Fillet018 fails as well while Fillet017 does not. So Fillet018 has to be investigated further. Try with less edges to fillet and smaller radius values for the fillet until you found the culprit. If you then still cannot see how to repair, come back here and describe what you found.