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Make sure the drive is powered adequately If the options are already checked, move on to the next fix.
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Tell us what you learn and do.Note: If it’s either of the last two, the mentioned fixes won’t work. Maybe someone who has actually had success with one or another method will see this and contribute. "Experimental" would keep me from trying it.
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It seems to me that you need some additional software, though some sites make reference to an "experimental" solution using Terminal commands. This site is fairly typical of the results of the search and is probably a promotion for one solution, iboysoft. I suggest googling "Big Sur NTFS" (without the quotes( to see a representative set of opinions. There are several offerings, Paragon being the only such company I have heard of but there are others.
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I wonder if you were using third party software in the past to be able to write to an NTFS drive. The combination of Big Sur and Macs with Apple Silicon seems to have taken even that limited function away as you are experiencing. In the past the typical situation has been that a Mac could read NTFS drives but not write to them. First of all, this is not a problem I'm having so whatever I have to say is Googling (Duck Duck Go actually.)
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