We've been doing a big push to clients to let them know about this so we don't have an emergency come January, especially as we still have some on older versions who have held off upgrading. Here is what I know about ISV's I've encountered so far.
Avalara - Compatible for 2018 and 2019, have not tried 2020 but expect it would be.
Scanco - Multibin, Manufacturing are NOT compatible with 2018.10, not yet compatible with 2019.4 (this is coming), compatible with 2020.0 (which does have the 1099 changes) but not compatible with 2020.1 yet.
DSD depends on the solution but I am finding that almost all are compatible, they are listed by solution with their compatibility
Hope this helps a bit!
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Jesse Braun
Vrakas/Blum Computer Consulting, Inc.
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