Hi,
I split your question, because there are quite a few issues in it.
1. "Invalid hatch area" means, that the selected entities doesn't surround an area, somewhere must be an openening. The opening may be very small, that it isn't recognized even with the zoom function.
Try the "snap to entpoints" function when drawing the area or enter the coordinates in the commandline.
2. The preview window seems to be corrupt. When the hatch dialog opens the first time, the preview is OK, but afterwards it doesn't show the patterns.
After restarting LibreCAD the preview again works one time.
I'll submit a bug report for this.
3. For circles, the hatch should work, except the preview (see 2.). If you create a hatch on a circle and see nothing in your drawing, please check the draft mode setting (Menu View->Draft). Draft mode is used to speed up drawing, hatches are ignored in this mode.
Armin
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