For the LLC where you expenses equaled your income, yes you must file a tax return.
For the LLC that had no activity, directly from the IRS Instructions for Form 1065 " every domestic
partnership must file Form 1065, unless it
neither receives income nor incurs any
expenditures treated as deductions or
credits for federal income tax purposes."
https://www.irs.gov/pub/irs-pdf/i1065.pdf
