Hi,
a flat pano is defined with a field-of-view of 1 degree by default.
And hotspots with zoom=true or distorted=true are using 90 degree ^= 1000px as reference.
That means hotspots would be extremely large in such case and would require a small scale value to become visible.
And the ath/atv values should be also within the -0.5 to +0.5 range.
Try adding scale="0.001" to your hotspots.
Best regards,
Klaus