QB Issue Resolution:

clearing the browser cache fixed it.

In case it helps others, I’m using Firefox 66.0.2 (64-bit) in Linux Mate (Mint)

Thanks again, Tim

Resolution for Issue 'Using Quickbooks Online sometimes I cannot open the Banking page. Other pages open as expected including the banking Rules page. Does anybody else have the same issue?' available: Yes (Solved).
Source: Intuit Community forum.

Using Quickbooks Online sometimes I cannot open the Banking page. Other pages open as expected including the banking Rules page. Does anybody else have the same issue?: 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 banking Rules
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Error Recovery for banking Rules [Canada]
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