A product isn't showing or isn't visible in StockTrim - why?

Firstly (sorry for stating the obvious) double check that it is in your inventory management system or is present in your CSV upload. This does happen more than you'd think.

Check the filters - are you viewing the order plan on a particular location? If so try removing that.

Is the product discontinued? These don't appear by default - select the discontinued filer to show it.

Is the product unstocked? It also doesn't appear by default - select the unstocked filter to show it.

Are there any other filters selected (eg: manufactured items or variants).

If it is in your IMS and not coming into StockTrim then double check the status of the product in your IMS - sometimes the IMS does not send through items via their API. Compare the product in your IMS with one that is coming through correctly.