I’m running Hassio 0.75.3 but this problem occurred in 0.74.x too. I have a “livingroom” tab in Lovelace but if Hassio reboots and some of the devices are unreachable then there is no information displayed in the tab. However I do get a popup that says “Service system_log/write called” and the error message there is http://192.168.2.52:8123/frontend_latest/eb618cf11a4eca6918ea.chunk.js:734:783 TypeError: this.lastChild.setConfig is not a function
This problem is either related to my LG TV or my Chromecast because if I turn on the TV (Chromecast is powered by TV) then the tab in Lovelace becomes available again. The tab remains available even after the TV and Chromecast are turned off again.