Hello,
if you make an Arc or Arc Center (0 to 270), then select it and enter a start angle of 180 the center will be moved.
Update: Because there was no feedback to this bug I add 2 screenshots to illustrate the bug.
Step one ... use ArcCenter to create part of a circle from 0 (right) to 270 (bottom) degrees
![ArcCenterPart1.png](//image.easyeda.com/pullimage/IqGWtPdNTUGLyOLcAuYX8IYq60zfSC9WBO46gMlE.png)
<br>
Step 2: Enter the value "180" in "Start Angle" ....
The value in "Start Angle" immediately changes to "90.0" and the value in "End Angle" changes to 0.0.
The origin of the arc moves one unit left und one unit down ....
![ArcCenterPart3.png](//image.easyeda.com/pullimage/yiJlnsCWPi2gjPSRxbVHX4dmY1qMN4DLOUCl5Ji0.png)
regards
Chrome
92.0.4515.70
Windows
10
EasyEDA
6.4.20.2