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the locallyPaused property of TimedItem includes the following text: 3. The next step depends on the current value of locallyPaused as follows, If locallyPaused is true, Record the current value of currentTime as pause start time. If locallyPaused is false, Set the stored value of timeDrift to the result of evaluating effective parent time - startTime - pause start time. The comparison values here for locallyPaused are backwards (i.e. if locallyPaused is false then pause start time should be set to the current value of currentTime).
Although I haven't traced down the exact changeset where this was fixed, I confirmed that it has been fixed in the latest ED.