most interior dressings use silicones, not 100% sure ez1 does though.
an APC is a degreaser.
Sounds to me like the two are just reacting with one another. A agree that a 4:1 water/apc solution is too strong, I personally use 10:1 for interiors unless the area is really really bad. Try a new solution of 10:1 or 20:1, whichever you perfer, and do a single door panel. Dry, then wet a towel with water and wipe down again. Dry, then use your interior dressing. It shouldn't be streaking now.
If it works, remove the water wipe step and see if anything changes. If not then your problem was definitely excess APC.
I've also had problems (rarely) in the past if I let my interior dressings sit too long. If you are spraying and wiping this isn't your issue, if you are spraying the whole car then wiping off, try another method.