This happened to me a few years ago also with an AAPL split. I was looking at my historical trends and noticed a large dip in July. Looking deeper, the stock prices prior the the 8/15 split for SWPPX showed post split prices for most days in July and August. I manually corrected them and all looks good now. I updated the security prices and my manual changes seem to have stuck. Raising for awareness in case others have this issue.