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My first thought is you are using a dimmer but you don't mention that specifically. If so you need to change to a specialised led dimmer to handle the lower voltage, v-pro are one of the most popular ones. You can change just the dimmer module and keep your switch plate / knob if you like.
Alternatively you can fit a ballast in the circuit, they are available from most electrical wholesalers.
I've got some old explosion-proof lights that use T30 E27 lamps. The ones they came with were too low output and I finally got round to replacing the original incandescents with LED replacements this weekend.
Each light has 4 lamps, if all of them are LED they come on for a fraction of a second then go off, if I then return 1 incandescent (so 1 incandescent and 3 LEDs per light) they work without issue. Is there some way that their significantly lower power draw could be causing this due to some circuitry/safety feature in them?