Anyone had any luck fixing this issue?  We just upgraded from Sage 100 2021 to 2024 and ran in to this issue.  We are invoicing about 1000 Sales Orders a day and 98% have a /C comment line at the top.  Any help would be appreciated.

This appears to be resolved in PU1.  If for some reason you can't install PU1 of v2024; then open a ticket with Sage requesting the fix. 
Sales Order  New in Product Update 1

Tax class is missing from tax code no longer appears when changing the Sales Tax Schedule on a
Sales Order Invoice, when the first line on the sales order is /C.

DevID 117076

I have a concern with how Sage handled this patch. I ran into this on 2022.6 and it was only because I was working on updating a customer site who also had payroll and unfortunately decided that "while I was in the system" that I should install the latest supported product update --- 2022 PU6.

The customer did not notice this issue occurring until I installed PU6

Sage opted not to release a product update 7 and instead the Sage 100 2022 last PU appears to be 6 -- which is where the customer noticed the bug.

The only option given to this customer was to sign a waiver for a fix for a supported version of Sage 100 where the bug appears like it could have been introduced by  Sage in 2022 PU6.

I'm confused as to why Sage wouldn't have issued a public patch on this if in fact it was a bug they introduced in 2022.6. Given this experience I've changed my recommendation to customers: 

1. Don't install a PU unless it clearly resolves a known issue that you are experiencing

2. PU won't automatically be released for supported versions

3. Sage no longer appears to be posting fixes to their download portal. It remains to be seen if this will be a permanent policy and, if so, whether all future patches will be "waiver required".

We are on 2022.4 and were told to upgrade to PU6 to fix a different bug but if installing PU6 creates a new but then we won't install it. I'm glad I saw this post before we installed it and were stuck.

Did it work?

I have 2 clients on patched/updated systems report this beginning 1/1/25.  It may be something on the Avalara side.

We have a client on 2022 PU6, which was installed at year end for the same reason you posted above.  They have the Sales Tax error since that installation.  We installed the hot fix LM7112-T but they still are getting the tax error.  Were you able to fix your customers error?

Does your customer use Operations Management?  If yes then there is a different hotfix for this issue on the Endpoint Download website at portal.jobops.com/download2022

No, just Accounts Receivable, no Sales Order module.

Make sure you have installed the program fix  Sales Tax Displays TAX ERROR.  If you have 3rd Party modifications, check the Links folder under MAS90 folder for SO_Invoice or SO_Sales order programs.  If they exist, contact the 3rd party vendor of your modification.  You can find this in the Library Master_Reports_Installed Module listing.    If there are no 3rd party modifications or any customizations there may be a flag from a prior attempt set to Y.     Do the following only if you are versed in using the Sage 100 Utilities and have a current backup.  In Data File Display and Maintenance, check the InvalidTaxCalc$ field in the SO_InvoiceHeader.m4t or SO_SalesOrderHeader.m4t tables.  That field should be edited to N.

I have confirmed that the hot fix is installed.  I think that the issue is that they don't user Sales Order, they user Accounts Receivable.  I think maybe the hot fix is for SO only.

On 2022.6 I entered an AR Invoice with a /C Comment as the first line and I don't get any TAX ERROR message.  Are you able to duplicate in version 2022.6?

On 2022.6 I entered an AR Invoice with a /C Comment as the first line and I don't get any TAX ERROR message.  Are you able to duplicate in version 2022.6?