Timers pulse when they activate from an inactive state even though the timer hasnt finished its cycle. In the attached image i have a timer turned off by a lever. The timer is set to 10 seconds. The instant you turn off the lever the timer instantly pulses and trips a set reset latch before the 10 seconds pass.

When you close a world and then load back in inverted buffers, set reset latches, and/or timers appear to have issues working correctly. In the attached image i have a timer (the left one) which is supposed to activate a set-reset latch which keeps an inverted buffer gate in a powered state. After the now enabled middle timer finishes its set time the pulse should flip the latch which turns the right timer back on to do what it needs to. However, when the world is closed and then reopened the middle timer will now instantly reactivate the set-reset latch when the buffer is powered which re-disables the wires and keeps the furthest timer from ever turning off. Breaking and replacing either the set-reset latch or the inverted buffer gate fixes the issue and gets the system working again until you next reload the world. Breaking and replacing the timer does not fix it. Oddly enough the setup works fine despite the previously mentioned timer pulse issue when first made, but only until the world is reset which breaks the setup.