Eric this is not specific to the new build but a problem, is cosmetic only as far as I can tell.
Using a zyxel 3924-B10B device, the sync uptime is reported as "AS uptime". I tried both 1312 and 8924 device type with same result.
I dont see anything actually wrong with all data collected, so this seems purely a cosmetic issue.
DSLstats uses the value "Since Link time = ..." at the end of the connection stats if it's available, and displays it as "DSL uptime". Some Broadcom firmware versions don't include this value, in which case DSLstats uses the AS (available seconds) figure, and changes the label to indicate this. There's an extra complication in that the "Since Link time" value stops increasing when the uptime reaches a certain maximum value (I forget offhand what it is, but I'll check). When this value is reached, DSLstats switches over to using the AS value, and changes the label.
This may all seem a bit pointless, but some time ago we encountered some modems in which the AS value didn't accurately reflect the uptime, so DSLstats uses "Since Link time" by preference.
[Later] the limit for "Since Link time" is 49 days and a bit (2^32 milliseconds). For simplicity DSLstats switches over when the time exceeds 49 days.