How did the items get into Physical Count Entry?  Using the Worksheet, VI or manually entered?

Using the worksheets

You should list your edition and version so this can be determined if it occurs for others on the same version.  Something else to check if you are familiar with Crystal Reports is to query the IM_Physical table and see if the FIFO items actually have value in the LotSerialNo field.  It could just be a bug with the grid being loaded and display it incorrectly.

Also, do you have any third party add-ons?

Have you tried to clear the frozen items and reselect them?

Were these items lot or serial at one point and changed to FIFO?

If you use Crystal Reports to query the IM_ItemCost table, do you see values in the LotSerialNo field for the items affected?

We sometimes see this kind of thing left over after a valuation type change.  Query IM_ItemCost and look at the TierType (...the help files will tell you what the different codes mean).  I don't expect the Freeze function validates cost tiers vs current valuation on items.

Sage100c Advanced 2018 (Version 6.00.8.0)

Third Party add ons (3 total): Avatax Connect, DSD Multi-Currency, and BCS ProSoft's Automated Rental Management

I have not tried to clear/reselect those items. I will try that now and report back.

These items were never changed from Lot/Serial to FIFO, they were imported using FIFO method

The only thing I see on an Inventory Valuation Report (We use crystal reports, but I can't edit any crystal reports settings on my machine) is the Receipt Numbers, which do not correspond to the serial number that's populating in the count entry window.

David, this did turn out to be a bug with the grid being loaded and displaying incorrectly. Version is 2018 Version 6.00.8.0