There were no changes to STIS for ETC 18.2.
The following bug was discovered to be present in 18.0 as well as 18.2:
On all STIS Spectroscopic forms, you may get the error “Internal error (no PEA found for this exposure)” This error is caused by a JavaScript glitch that sometimes occurs when the user selects an extended source and clicks on the “Use a region of height N pixels” button under the point source selection. This is an occasional glitch, and will usually not occur again if you enter your form data again (or simply hit the “Back” button) and then submit again. If you do encounter this error and it does not go away when re-submitting, please contact the helpdesk to report the issue.