Gecko codes are currently broken in master (since 5.0-619). It's a known regression from a CoreTiming cleanup. PR 4216 fixes that, but no one has merged it yet.
Quote:However, if I use the Ishiiruka fork, it all runs flawlessly with gecko codes.Ishiiruka is based on the master branch, but it's not always up-to-date, so it may not have integrated the latest changes (and the regression) yet. Or it may have integrated them, but applied to fix or reverted the commit that causes issues.
Any clues as to why Dolphin won't work with them but Ishiiruka does?