QB Issue Resolution:

Turn on inventory first, Click the gear (upper right), Click settings>company settings>Products & Service
left side menu products & services Click Track Qty on Hand

see the pic for a new inventory item screen

Resolution for Issue 'cant find where the inventory is' available: Yes (Solved).
Source: Intuit Community forum.

cant find where the inventory is: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Inventory
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Error Recovery for Inventory [Canada]
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