Have the roots outgrown the pot?
A root at the drainage hole is a clue. Check how densely the roots fill the pot.

What to check first
If the plant slides out easily, look for a dense mat of circling roots with little mix left. The pot may dry very fast or drain immediately while the middle stays dry.
What to do now
If the roots are crowded and watering no longer works well, move the plant into a pot one size up with drainage and a mix suited to it. Leave firm, healthy roots intact where possible.
What to watch next
See whether the new mix wets evenly and dries at a reasonable pace. If the plant wilts while the new mix stays wet, check moisture and drainage before watering again.