Can't put arrows on end of stroke.

Before you put a bug note in ...

Try rebooting perhaps?

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If a document is not behaving well then try 

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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Try resetting your preferences:
The easiest way to reset everything is to delete the InDesign preferences: as soon as InDesign starts to boot hold down Shift, Alt, Ctrl (and Apple/Cmd if working on a Macintosh). 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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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

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Rollback to a previous InDeisgn version

https://helpx.adobe.com/download-install/using/install-previous-version.html#:~:text=Open%20the%20Creative%20Cloud%20desktop,down%20list%2C%20select%20Other%20Versions.

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Report bugs or make a feature request

https://www.adobe.com/products/wishform.html