Try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"
• https://hacks.mozilla.org/2010/09/hardware-acceleration/

• https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I disabled hardware acceleration in Firefox. Checked all of my drivers so they are up to date and disabled all of the add ons. None of that helped, the cursor actually blinks repeatedly now instead of disappearing when not in use.

You may have switched on caret browsing.

• http://kb.mozillazine.org/accessibility.browsewithcaret

You can press press F7 (on Mac: fn + F7) to toggle caret browsing on/off.

• Tools > Options > Advanced : General: Accessibility: [ ] "Always use the cursor keys to navigate within pages"

• http://kb.mozillazine.org/Scrolling_with_arrow_keys_no_longer_works
• http://kb.mozillazine.org/Accessibility_features_of_Firefox

That still did not do the trick. I have toggled the caret browsing (it was off initially) and the problem still persists.