I'm not rocking 2018.1 yet so can't open it up but you should be able to right click on your axis and select 'synchronize axis'. If it is disabled, you need to set both your fields to the same type. Whole, decimal, etc.
Thank you so much for your feedback.
I'm not sure "synchronize axis' is available for the x axis. I uploaded a lower version. If you could look at it and let me know what you think.