Hi @AlexMcomm ,
Could you please share a screenshot about the issue within your app?
How do you add the button in your data cards within your app? Do you insert the button within the data card or outside the data card?
Please make sure you have added the button within (inside) the data card in your app, then the button would be fixed to the corresponding data card:

In addition, please make sure the inserted button is relative to the data card, e.g. set the X property of the button to following:
DataCard1.Width/2-Button1.Width/2
set the Y property of the Button to following:
DataCard1.Height/2-Button1.Height/2
Please consider take a try with above solution, check if the issue is solved.
If the issue still exists, please consider turn off the "Scale to Fit" option within "Screen Size + orientation" option within App settings of your app, check if the issue is fixed.
Best regards,