Webviewer don't display button

[TIMAI2]

Try with this extension

WebViewExtra - Upload/Download Files with webviewer (and much more...)

WebViewExtra [wveicon] An extension for AI2 that extends the features of the native webviewer. The extension, by default, will provide the following features: allow for uploading of files from within a webviewer. (Developers will need to provide suitable html solutions...) allow for downloading of files from within a webviewer, even from Google Drive shared folders! Files are saved to the Download directory in Shared storage. sets READ and WRITE in the app / aia project, enabling the setting…

it changes the userAgent

Your buttons then show OK