Just to double check that you have the text tool selected and it's active within the text frame - that is type some text and delete it - to make sure - then try.
If that's not working
File>Export
Choose IDML
Open the IDML in InDesign
Save the file as a new InDesign file with a new name
See if the issue persists.
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If that doesn't work
Try resetting your preferences:
Windows: Start InDesign, and then press Shift+Ctrl+Alt. Click Yes when asked if you want to delete preference files.
macOS: While pressing Shift+Option+Command+Control, start InDesign. Click Yes when asked if you want to delete preference files.
A dialog will appear asking to delete the InDesign Preferences, select 'Yes' on this dialog.
Further info and instructions here if needed:
https://helpx.adobe.com/in/indesign/kb/indesign-preferences-support-file-locations.html
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If it's still not working
Reinstalling rarely fixes everything - you can do a complete reinstall using the
Creative Cloud Cleaner Tool https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html