Hi, Tolkien, thanks for your feedback. Firstly, the Excel formula =MID(LEFT(A1,FIND("end_char",A1)-1),FIND("start_char",A1)+1,LEN(A1)) only can extract text string between two single characters. And the Formulas Helper of Kutools for Excel, I have tested in Excel 2019, 2021 and Office 365, it can extaract string between "Format:" and "," whatever if the string is begins with "Format:", please see the screenshot attached.
Could you tell me which Excel version you use? Amd should you upload the data and formula result screenshot for me to better realized the problem? Thank you.