Copilot returning document context error

I was using Copilot in PowerPoint to create presentations from Word files, without problems. Without changing anything, PowerPoint suddenly started returning an error when I opened the Copilot pane.  This issue is only occurring on one computer, whereas my other laptop, using the same account, is working properly. I have tried signing out/in of my account and also reinstalling 365 on this computer. 

Error code:
Error Message: Cannot read properties of null (reading 'DocumentContext')
 Error Stack: TypeError: Cannot read properties of null (reading 'DocumentContext')
    at https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/appchat.js:1:841804
    at Object.useMemo (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:100202)
    at t.useMemo (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:34060)
    at _i (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/appchat.js:1:841672)
    at ua (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:94279)
    at Xl (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:146207)
    at zu (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:133543)
    at Iu (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:133471)
    at Ou (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:133334)
    at Cu (https://fa000000129.resources.office.net/033f92d3-bc6d-439a-858a-a17acf70360a/1.0.2509.1003/en-us_web/taskpane.js:2:130331)