Experienced the following problems while testing (New) Map Viewer (10.9.1, Enterprise):
(1) Any change/save in the Map Viewer results in the loss of the predefined forms for layers in the field map (same as the earlier Map Viewer Classic (10.8.1). There was no loss in the earlier Map Viewer Beta (10.8.1).
(2) In the Styles, attributes Expression does not work.
Example: I tried with IsEmpty($feature["XY"]). Here XY is a date field. The object having 'no date' in the XY (i.e. true) should be visible in a colour and having 'date' should be visible in a different colour. This is not working, also when applied with a 'string' field.
(3) Filter starting 3 expressions results in an instability. Often the result is "Expression cannot be shown properly, Try again" and sometimes the filter works.
(4) In the new Map Viewer, there is option to configure attributes under the pop-ups configuration to make data invisible to the field works, who may otherwise edit data in the portal.
Appreciate any support/idea.