We are investigating problems in Storage which could lead to inappropriate processing of incremental loading and related functionality. We will keep you updated.
UPDATE Jan 29 9:45 CET - Problem is that incremental load from transformations is not setting _timestamp column. We had identified a release that was causing trouble and finished its revert. Unfortunately, already created table rows having the _timestamp with null values still won't be processed by incremental loading. You can fix this situation manually by running a full load. Now we are running tests to isolate the root cause and preparing global correction of its side effects.
UPDATE Jan 29 14:00 CET - The _timestamp values are written correctly for all newly added table rows since the morning release revert. So now the problem persists only with the rows added previously (ca during yesterday and today's night) which still contain empty timestamp values and so won't be processed e.g. by writers configured to incremental loads. (You can overcome it temporarily by setting them to full load.) Now we are working on backfilling missing timestamp values and so fixing the incremental functionality for these affected data.
UPDATE Jan 29 18:00 CET - The backfill of missing timestamps is being prepared and should be ready tomorrow.
UPDATE Jan 30 15:00 CET - The backfill mechanism is released. Now we are performing last checks before applying it to all affected data.
UPDATE Jan 30 16:30 CET - Unfortunately, we are forced to leave the backfill for tomorrow. There is an incident in Travis CI which is slowing down our work the whole day and is still not resolved and we decided not to risk running it rashly during the night to be able to support it properly if anything goes wrong.
UPDATE Jan 31 10:30 CET - All preparations are done and preliminary test finished. We are just starting with the backfill.
UPDATE Jan 31 12:00 CET - The backfill is running and ca. 10 % of affected data is fixed.
UPDATE Jan 31 14:00 CET - The backfill is running and ca. 20 % of affected data is fixed.
UPDATE Jan 31 15:30 CET - The backfill is still running and ca. 25 % of affected data in US region and ca. 40 % in EU region are fixed.
UPDATE Jan 31 17:00 CET - The backfill is still running and ca. 70 % of affected data in US region and ca. 100 % in EU region are fixed.
UPDATE Jan 31 17:30 CET - The backfill is finally finished. All the affected data are fixed and have _timestamp column set to "2020-01-29 00:00:00". So that you should update your settings if you have incremental loads set to lower value then 3 days.