It has happened to me that even Firefox crashes.
My solution is to reload the lab and locate myself where there is good Wi-Fi signal coverage 
It’s not a guarantee, just reopening Firefox may resolve it
In the Spearphishing labs (Spearphishing with a Link / Spearphishing with an Attachment) there are no active Wazuh agents. Be sure you are looking at the wazuh-archives-* index and be sure you have set the date correctly (Mar 14, 2024 @ 00:00:00 to Mar 15, 2024 @ 00:00:00)