Fun Guideline story: I worked for a company that went bankrupt and used guideline for 401k. The first day the website allowed me I withdrew the balance for rollover. Apparently this should not have been possible before the bankruptcy was finalized. I found from court filings that the bankruptcy trustee kept telling Guideline they need to freeze withdrawals until the bankruptcy was finalized, and Guideline kept dragging their feet and acting like they didn't understand. The trustee ended up having to go to court and get a temporary restraining order to prevent more employees from withdrawing their balances before the bankruptcy was finalized.
Un-fun bankruptcy fact: All employee names & mailing addresses are part of the public record and accessible on PACER because they're potential creditors in the bankruptcy.