Hello Geoff, it may just be still asleep, still dormant.
Are you able to re-position this plant outdoors in a part sun area? Your location is in mid Spring heading to Summer, just the perfect time, to gradually awaken the plant. If your outdoor overnight temperature is at least 10C and higher, it is safe to bring it out. I do not know if your area is rainy. Try to protect it from rain at this time, it is not yet awake.
Adenium responds nicely to warm temperatures, lots of direct sun once awake, and gradually takes in the hottest temps it can take when summer is around. As temps go higher it will then appreciate stepped up watering. It just all depends if it is awake already. Sometimes, it will do blooms first, but it does not mean it is awake, got to see new leaves forming.
In the meantime, continue to be patient, it just needs to wake up some more. Feel the caudex, if it is staying firm, no mushy part anywhere, it is okay. You can also decide if you want to lift the base of the plant some more, to expose more of the caudex that has formed below soil line. I like to do this step, while my plant is still sleeping. I do not move it to any bigger container, but I do use this time to check further the condition of the roots, improve the soil mix as needed, so it is ready to do its active growing once ambient conditions warms up further. I do not water yet if I do lift the plant. I just allow it to settle some more, and once new leaves show up, then I can start watering.
