a Turbotax pro I spoke to on 8/27 said the issue was fixed in the online version with the 8/26/2021 update. if that's the version you're using evidently not. I use desktop deluxe. the pro had a work-around for this version by using step-by-step and not forms mode. she was supposed to contact me when there's a fix. haven't heard from her yet. it works for current year additions but I just found out there's no way to correct prior years assets. depreciation computes correctly for prior years assets but you get the error on review which probably would prevent e-filing.
this bug has existed for several weeks now and supposedly was to be fixed with the above update. contact support. the more of us that complain, hopefully, the faster they'll come up with a fix without introducing other bugs. this bug was introduced with an update that was to fix other bugs.
