A computed value in process.js doesn't show up in the PDF

See Debugging.

A block renders nothing, but there's no error message

See Debugging - usually by design, not a bug.

form.json won't open / "missing a required field" error

form.json needs, at minimum, a title and a fields array (even if empty). If you hand-edited it and see a "missing" error, check for a typo'd key name or a JSON syntax error (a trailing comma, an unclosed brace) - the Script Editor doesn't validate JSON as you type, so a stray character is easy to miss. A project that otherwise fails to load is simply skipped in the Projects list rather than breaking the whole list, so if a project you expect to see is missing, that's the likely cause - open it from a regular file manager to inspect form.json directly.

Layout looks right in the editor but the printed PDF looks different

The Layout Editor's canvas only ever shows and edits page 1 - if your project uses a multi-page base.pdf, anything you've placed on page 2+ (via hand-edited page properties, see Layout JSON) won't be visible while editing, only in the final PDF.

Blocks look shifted after regenerating base.pdf

Create base.pdf replaces the canvas at a size you choose - every block's x_mm/y_mm/width_mm/height_mm stays exactly what it was, so if the new page size differs from the old one, everything will look shifted relative to the new canvas. Re-check block positions after resizing the canvas this way.

Autocomplete isn't suggesting anything for a field

Two requirements, both manual - there's nothing that fills in automatically:

1. The field needs an Autocomplete Key set in the Form Editor (or autocomplete_key in a hand-edited form.json).
2. autocomplete.json needs a matching key with at least one value in its list - see Autocomplete JSON. Suggestions never come from anything someone previously typed, only from what the form's author has put in that file.

I made changes and don't see a save option

The app only surfaces Save when there's actually something unsaved - the Layout Editor and Form Editor both show a * next to the title and a save icon the moment anything changes; the Script Editor's Save button enables the same way. If you don't see either, there's nothing pending to lose.