Adult dog started peeing inside

My 7 or 8 year old american foxhound has started peeing inside in the last few months. She almost always does it when she is home alone, one night she did it in the middle of the night while I was home. Her routine has not substantially changed, in the past I've left her alone for the same amounts of time/same frequencies with no issues. I take her outside right before I leave every time, and I leave her at least 3 or 4 enrichment toys every time so she is busy. From what I can tell by checking the camera, she is not in distress, she is usually asleep when she finishes her enrichment. She has also done it at my mom's house when she spends the day there while I'm working, also only when she is alone. We went to the vet last week and she has a clean bill of health. I make sure to clean the spots fully. Any ideas on what could be happening/what we can do to resolve the issue?