Hello Klaus!
Here are a few bugs that I found.
Do you know these bugs?

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<krpano version="1.19">

<hotspot name="hs0" style="test" distorted="true" ath="-10" atv="-10" rotate="45" scale="0.3" keep="true" /> <!-- Rotate incorrect -->
<hotspot name="hs1" url="hs.png" distorted="true" ath="+10" atv="-10" rotate="45" scale="0.3" keep="true" /> <!-- Good -->

<hotspot name="hs2" url="hs.png" distorted="true" ath="-10" atv="+10" rotate="45" scale="0.3" keep="" /> <!-- Visible -->
<hotspot name="hs3" url="hs.png" distorted="true" ath="+10" atv="+10" rotate="45" scale="0.3" /> <!-- Not visible -->

<style name="test" url="hs.png" />

</krpano>

Here's my solution to the problem.
You need to add a decimal value.

<hotspot name="hs0" style="test" distorted="true" ath="-10" atv="-10" rotate="45" scale="0.3" keep="true" /> <!-- Rotate incorrect -->
<hotspot name="hs0" style="test" distorted="true" ath="-10" atv="-10" rotate="45.0" scale="0.3" keep="true" /> <!-- Good -->

<style name="test" url="hs.png" />