Yes, if a field is not available in Custom Filters, it is often because it is either:

• A non-stored computed field (store=False), or

• A field that does not define a search method.

In the case of Last Counted on the Physical Inventory view, Odoo calculates the value from the inventory adjustment history rather than storing it directly on the record. Because of this, it cannot be used directly in search domains or custom filters.

To identify products or locations that have not been counted recently, you can instead use the underlying inventory adjustment data. Depending on the model used in V19, the "Last Counted" value is typically derived from the latest inventory count date associated with the stock quantity (stock.quant).

A practical approach is to:

• Add the "Last Counted" column to the list view and sort by it.

• Create a custom stored field that captures the last inventory count date.

• Or create a custom filter/report based on the inventory adjustment records that calculates the latest count date.

You can confirm whether the field is stored by enabling Developer Mode and inspecting the field definition in Settings → Technical → Database Structure → Fields. If store=False, that explains why it is unavailable as a custom filter.