PIC32 I2C not operating as expected
The problem turned out to be a bad connector on the logic analyzer.  It is a 34-channel LA, but we tended to use just the first few channels over and over.  Apparently the female jack for the SCL line, which accepts a pin like those on 0.1" headers, had become flaky.  I should have realized it was something to do with the LA when I got the same results with the Bit Whacker.

I looked at the signals with a scope, and both the SCL and SDA were high when idle, and when low with the start protocol.

I picked a different set of channels on the LA, reconfigured the I2C interpreter to use those instead of the first two channels, and got a nicely interpreted I2C protocol.