CHICAGO — Injury issues are not going away for the Chicago Cubs. Some players are moving in the right direction. Right-hander Alec Mills and left-hander Sean Newcomb made rehab appearances at Triple-A Iowa on Friday while Clint Frazier was activated from the injured list Saturday before the City Series opener against the White Sox at Guaranteed Rate Field. The outfielder missed 31 games because of an appendectomy. Michael Hermosillo was transferred back to the 10-day IL while left-hander Brandon Hughes, who was brought up from Triple-A as a substitute player during the Cubs’ COVID-19 issues, w…