Cannot select repair ship for repair anymore

[BananaConvention]

Up until about 3 turns ago, I was able to use my repair ship to fix ships. Now suddenly, the open is not available and I can't understand why. I am trying to enter a sub into a repair ship for repair, but no matter what I've tried I cannot click "repair ship" even though I had several other subs cycle through the repair ship prior.

Here is the ship I am trying to repair. Clicking repair mode does nothing, it won't advance past pier side:




This is the repair ship I had been using to repair subs at Truk. I cannot understand why it won't work now, it was working a few days ago. Nothing has changed:



Please help me figure out why this stopped working.

[Nomad]

ARDs will only repair floatation damage, the sub has major engine damage.
You need either an AR or a level 7+ port.

[Capt Hornblower]

More explicitly, the vessel you wanted to select to perform the repair is a floating dry dock and, as Nomad said, can repair only flooding damage.

[Leandros]

Good to know - I have had similar problems.

Fred