not saying this is the reason but each activities 179 is computed on its own but then all the separate activities must be combined to see if you exceeded any of the limitations
Line 1
Generally, the maximum section 179
expense deduction is $1,000,000
Line 3
The amount of section 179 property for
which you can make the election is
limited to the maximum dollar amount
on line 1. This amount is reduced if the
cost of all section 179 property placed in
service in 2018 is more than
$2,500,000.
for example say you claimed a total of $1,200.000 in 179 in total from the separate activities
and you are not subject to the reduction on line 3
business income limit is $700,000
so $700,000 is allowed
$300,000 is carryover
that extra $200,000 in 179 is lost!!!! - no carryforward,
another possibility is that you have a business activity with a loss. This will reduce the allowable 179 only on the summary 4562
there should be a summary 4562, review it.
if this isn't the issue contact support since we can not see your returns
https://ttlc.intuit.com/community/turbotax-support/help/03/313
I had this same error which turned out to be an omission in Turbo Tax. Turbo Tax corrected the problem in a special update:
You may want to try this or call Turbo Tax Support for guidance.