I am using a custom page in a model driven app. Inserting a gallery of type Blank Flexible Height Gallery creates an issue with a textinput box added to the template. When I preview or play the custom page and type data into the textinput box, the data is not captured. It returns to the original value (whether blank or something else).
It seems this is only an issue with this type of gallery.
In the screenshot below I typed 123456 into both galleries on the top line. When I navigate away from the textbox in the "Blank Flexible Height Gallery" the value returns to "Text box" and entered value is not captured. On the "Flexible Height Gallery", the input persists.
Do you have the same Default property in the Textinput box in both galleries? I am not seeing that behavior in my test. Both galleries work the same way.
There is no default property for this input. The textinput on the custom page has different properties than a typical canvas app. While Canvas App text input has "Default", "Text" properties, Custom Page has a property "Value". Basically, in both galleries I added the textinput from the insert menu as-is and kept all the default values that come with the control. Trying to compare apples to apples.
I am having the same issue in a teams canvas app when using the modern controls (.Value), using the classic control works (.Text). The Text Input works outside a gallery, but not inside the gallery.
Don't use the Blank Flexible Height Gallery. Choose the other "Flexible Height Gallery" and then delete the controls you don't want. It seemed to be just a problem with the Blank Flexible Height Gallery control.