I've had the exact, same problem (first one or two are scaled properly, then it gets erratic).
I've complained about it more than once, but haven't been able to provide a repeatable sequence of commands to replicate it.
While not certain, I'm inclined to think that the problem occurs near some invisible border that TurboCAD uses when it creates Draft views. It could be related to a problem with dimensioning several versions ago when applying a Dimension to a feature in a Paper Space Viewport caused a zoom-compensation error if the text was placed outside the Viewport's boundaries, even though the Dimension was started inside those boundaries.
TC Pro Platinum 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1