I had a similar experience recently. Actually had the water pump rebuilt, then reinstalled it in old A-4 in an old Triton.

No water. Actually, hot water came back from the engine to the raw water strainer.

I unhooked the hose from the pump to the block-- it was pumping water ok.

Clearly there was blockage in the engine. I unhooked the crossover from the block to the exhaust manifold. I could not even blow air throught the manifold. It was easy to blow air through the block.

So my problem is to remove the blockage from the manifold, which I have not yet done. Options are to try a slow marsolve drip (might work, might not) or bit the bullet and disassemble the manifold from the block and take it to a radiator shop to get it boiled out (I guess -- I've never done that, but I've seen references to it).

So, my advice would be to unhook the hose from the block and see if there's any water moving.

If not, the other possibility would seem to be that the pump is not primed.