Hi wonder8,
Thank you for your purchase.

Yes that is normal behavior of wpdatatables. From first screenshot we can see that you point on option Skip thousand separator which is intended for integers in tables. Every chart engine have own settings for formatting numbers in charts(in your case in tooltip). If you need different settings(that are not built in) for charts you can check in our documentation about wpDataCharts callbacks . 

• Please note that using hooks or wpdatatable or wpdatachart callbacks requires certain level of programing skills and included support refers only to advices.

• Every chart exposes several options that customize its look and feel. Charts usually support custom options appropriate to that visualization. wpdatachart callbacks  allows adding options that are available in Google Charts API, Highcharts API and Chart.js API. 

• All necessary rescuers are available in charts engines API(depends which one you use) .Every engine have different approach of charts settings. In wpdatachart callbacks you have to adopt those settings to wpdatachart object(you can take a look a examples for each engine in our documentation and also in Support help center). Huge number of examples for any area of programming you can find on stackoverflow.com(typing your problem in google and of the end add site:stackoverflow.com and google will search only on that website) and also a lot of resource of examples of chart, chart settings and customisations you can find on jsffidle. net(typing in google for example line chart highcharts jsffidle)