HomeKit automations not working (after 11.2.6?)

Hi

for about a week or so now, I've noticed that Homekit automations have largely stopped working. This is everything from timers to triggers. For example;

• I set a timer for lights (or other devices) to come on at a certain time - this has become random in that sometimes they work, sometimes not.
• I set automations where lights will come on, based on a trigger from another device, and then switch off after a set amount of minutes - lights will no longer switch off after set times.
• I set trigger based on a signal from another device (motion sensor etc) - these have largely stopped working altogether. I have various sensors and it's the same across the board, so it isn't an issue with a particular brand or specific device.
• I set a trigger based on the status of of a device (motion sensor) - for example, 'no motion detected, turn off light). No longer working.

All of this seemed to coincide with me updating my iPhone and Apple TV4K to iOS 11.2.6, although this could be a mere coincidence. I've also since found via Reddit that this has been happening to others all around the same time. If anyone can she any light on this issue and even a possible solution, I'd be grateful, as it's very frustrating find lights have been on all night when they should have turned off automatically.