Not OP, but much writing advice with which I'm familiar, and my own experience, both suggest these are symptoms of an error made earlier and not yet recognized.
If I can't figure out where the plot could possibly go from here, go back and look for where I sent it off the rails earlier such that there's nowhere to take it now; if I can't find dialogue or action that fits, go back and find where I put the character in a situation they'd never get themselves in, or miswrote them to respond to it in a way they never would. Stuff like that, especially once it's had you stuck too long for inspiration latency still to be tenable as the cause.
If I can't figure out where the plot could possibly go from here, go back and look for where I sent it off the rails earlier such that there's nowhere to take it now; if I can't find dialogue or action that fits, go back and find where I put the character in a situation they'd never get themselves in, or miswrote them to respond to it in a way they never would. Stuff like that, especially once it's had you stuck too long for inspiration latency still to be tenable as the cause.