As shown in Pic1.png, duplicants' navigation range through the liquid body seems to be limited to 4 blocks away from the ladder, meaning that the queued Dig job at the far right end is stated as Unreachable. However, if I manually move duplicants into the water, their navigation range then expands to the entire water tank, as shown in Pic2.png. This would then allow them to complete the Dig jobs naturally.
I suppose the bug heSubterranean Spacepad.savre is that the dupes' navigation range is incomplete if they are not actually inside the body of water.
Steps to Reproduce
1. Create a tank at least 8 blocks wide 2. Place ladder at extreme left side 3. Fill tank with liquid 4. Dupes' navigation range does not extend to extreme right side of tank 5. If dupes are manually moved into the water, their navigation range will then extend to the extreme right side of the tank.
This issue has not been confirmed by a developer yet.