An LLC provides liability protection for any and all debts or obligations incurred in the name of the LLC. If the members personally guarantee any LLC obligation, the entity structure will not protect the members from such obligation.
Also, if the members have not operated the LLC properly (i.e. did not maintain a separate bank account, did not enter contracts in the name of the LLC, did not keep accurate or sufficient company records, etc.), then creditors may have the opportunity to “pierce the veil” of the LLC entity and pursue the members personally for any LLC obligations.