Do you have any other phones with QC capability you can test it on? I tried mix/match chargers and cables and had no issue with getting the phone to quick charge, but like I said, all my chargers and cables come from other Sammy devices (S8, Tab S3, Tab S Pro, two Note 7s (RIP)).
The only thing I noticed is that, although it still charges faster, the phone doesn't say 'quick charging' when using my QC 2.0 compatible car charger that worked fine with the S7E. I've tried it with the original cable and a microUSB-to-USB-C adapter and with the cable from Samsung and still doesn't 'recognize' it as QC, but it did that from day 1, so...