The inspector tool isn't working (prior to restarting) I searched the question on google, and found a closed ticket from 2016, where I tried the different solutions provided by the support staff without any effects. Opening a new firefox window fixed the problem along with, opening inspector in other tabs, swapping between with open tabs with inspector open isn't an issue. Only the specifc tab I've been working on for a few hours that have stopped working and causes issues (sort off I guess). Opening my local development in another tab / window didn't reproduce the problem, so I guess some bottleneck has happened over time with extensive refresh and dom updates (Was working with styling atm). Anyway, as off posting this question, I plan on closing my defect tab, and use the other development tab I recently used for testing the bug related problem. reference: https://support.mozilla.org/en-US/questions/1112797