QB Issue Resolution:

If they show in the register but not on the reconcile screen, are they reconciled?  Look in the register to see the cleared column.  If it shows an R, it means it is reconciled.  So you may need to undo the bank recs and re-reconcile.

Resolution for Issue 'Transactions from the account register don’t appear when I try to reconcile. How do I find/reassign those missing transactions if they are in the register?' available: Yes (Solved).
Source: Intuit Community forum.

Transactions from the account register don’t appear when I try to reconcile. How do I find/reassign those missing transactions if they are in the register?: 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 Account Register
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