Slider range totally off

I’m trying to setup a simple demo code where a blynk slider controls an RC servo. I have two issues with this. One is already discussed in several threads about the need of debouncing when using serial printout. My other issue is that the end values I specify in the slider settings does not apply. For instance, I would love to have a slider with the range 450-2200 to represent the pulse length of a general RC servo (in µs). But as soon as I specify this large values, or a non-zero at either end, the actual range becomes -10k to +10k. I’ve confirmed this by both sending back the value to a blynk gauge and printing it over serial port.
E.g. setup slide (small or large, same error!) to 450-2200 range. Slide it. The small value at the slider in the blynk app displays the desired numbers. The number received in the program has the corresponding value with ranges set to ±10k.

Hello. Android or iOS? Also video of issue would be very helpful.