Thank you for taking the time to visit the Community and report this issue, though I apologize for any inconveniences this may have caused you.
In order to help us better assist you, could you please elaborate a little more on this issue? What exactly does the prompt asking you to sign in to Schwab say? Has this message appeared more than once? Can you recreate this message? Have you noticed any other errors related to this/these account(s)? This background information will be very important in diagnosing the cause of this message.
If you can, would you please provide a screenshot(s) of the message(s) you described receiving? If needed, please refer to this Community FAQ for instructions on how to attach a screenshot. Alternatively, you can also drag and drop screenshots to your response if you are not given the option to add attachments.
FAQ: How do I post a screenshot in the Community from Windows?
FAQ: How do I post a screenshot in the Community from a Mac?
Sometimes a picture is worth a thousand words... When posting here in the Community, it is very helpful to include screenshots of what you are seeing, to help others help you.
Once you have gathered this additional information, please reach back out to us so that we may assist you further. Thank you and have a wonderful day!