Hi,
1. check selection filters
2. please share the file*
3. Try CLEAN UNINSTALL
günther
*File > export > save as f3d on local drive > attach it to the next post.
hard to say without seeing the model itself, but it sounds similar to this one: cannot-edit-sketch-rectangular-pattern-pattern-icon . So, try turning off constraints in the sketch palette, then back on:

Pattern of sketch is almost always incorrect technique.
Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?