I tested and I experience this with single album files with both external CUE files and with internal embedded CUE sheets with 18.0.129.
I then installed 18.0.106.
Interestingly the embedded CUE sheet information in the library that was produced by 18.0.129 was still usable by 18.0.106 .
And, indeed 18.0.106 does not have the problem.
This time I used an album that was familiar and the bug is this:
It plays the first track fine.
If you use NEXT button to move to the next track (before the track reaches the end, it works fine.
If MC18 goes to the next track automatically, then the progress/seek bar will not move, the elapsed time does not increment and
the time remaining is set to an overly large time (this seems to be THE BUG).
When the time remaining reaches the Library Database value for the track duration, then the Elapsed Time and the Progress/Seek bar start working normally.
When the Time Remaining hits zero, MC18 goes to the next track ( even though the audio data for that track may have already been played ).
I'll bet a beer that fixing the Time Remaining fixes the problem.