EncoderManager.exportSequence(): no-preset fallback depends on opening Export mode, then queues only after cancelling a 0% dialog

Premiere Pro
,
1

The EncoderManager.exportSequence() documentation says that when no output file and preset are specified, applied export settings or standard export rules will be used. Could Adobe clarify the intended behavior? I can reproduce the following on an Intel Mac with Premiere Pro 26.3.0, UXP 9.3.0, and Media Encoder 26.3.1.

With an active sequence, I call:

const ppro = require("premierepro");
const sequence = await (await ppro.Project.getActiveProject()).getActiveSequence();
const encoder = ppro.EncoderManager.getManager();

const result = await encoder.exportSequence(
  sequence,
  ppro.Constants.ExportType.QUEUE_TO_AME,
  "",
  "",
  true
);
console.log(result);
  1. Before this sequence has been opened in Premiere’s Export mode, the call promptly returns false. No AME job is added.
  2. I open Export mode for the sequence. It shows H.264, “Match Source – Adaptive High Bitrate,” and an output location. I return to Edit mode without exporting.
  3. The same call now shows “Preparing data for export” at 0%. Its promise remains pending for more than 20 seconds. When I cancel that dialog, an AME job appears with status “Ready,” using the settings and output location shown in Export mode, and the original promise resolves true.

Actually omitting both path arguments (exportSequence(sequence, QUEUE_TO_AME)) produces the same pending-dialog/late-true behavior after visiting Export mode. As a control, supplying a valid .epr works without first opening Export mode. Supplying an explicit output path but an empty preset returns false.

For ExportType.IMMEDIATELY, both empty paths—or both arguments omitted—throw Invalid parameter., even after visiting Export mode. I also saw a similar 0% stall with the no-preset AME call in Premiere Beta 27.0.0 on Apple Silicon.

Could you clarify:

  • Should the no-output/no-preset fallback work before Export mode has been opened, using the documented “standard export rules”?
  • Is this fallback intended only for QUEUE_TO_AME, or also for IMMEDIATELY?
  • Is it expected that cancelling the 0% preparation dialog adds a Ready job and resolves the promise with true?
  • What is the supported way for a UXP plugin to request Premiere’s built-in default export preset while specifying its own output path, without providing an .epr file?

We’re trying to provide a reliable optional-preset workflow in a Premiere UXP plugin, so knowing the supported API contract would be very helpful.