[Bug] stack bar with only encode.y cannot be stacked

[Justin-ZS]

Version

5.6.0

Link to Minimal Reproduction

demo

Steps to Reproduce

If there are only values in the dataset.
Using encode.y and stack bar cannot stack the bars
I tried to add a dummy data: [ '' ] to xAxis, still doesn't work

Current Behavior

bars are not stacked

Expected Behavior

bars should be stacked

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

No response