This may be a possible bug. When loading a prebuilt form in the pdfViewer, the radio buttons do not seem to work. I tried clicking on them as much as possible, but all that is displayed is their field, but it seems to do nothing. On a side note, does the viewer support radio buttons which have different styles such as cross?
I am working with pdfViewer 18.104.22.168 on a Galaxy Tab S3.
Attached is a simple form which I use am using to test.