i use seamonkey (32bit) (basically mozilla) browser on windows 7/64bit and see this and a "just now" scenario too,
ie: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 SeaMonkey/2.49.2
sequence to reproduce "just now":
start on the earnings tab, then click on the settings tab.
then use the browser BACK button to go back to earnings without adding coins (i usually adjust payout proportions) but you
dont have to do anything at all.
first update on coins currently being earned gets a "just now" time stamp.
subsequent updates stay stuck on "just now"
hitting page "reload" puts everything back into working order.
sequence to reproduce "invalid date":
starting at the earnings tab, click on the settings tab, select a new coin you dont have any current balance for to earn.
click the browser BACK button.
you get the "invalid date" timestamp on that new coin when it appears as earnings.
hitting page "reload" puts everything back in working order.
i've just assumed it was my browser having a weird interaction between caching and javascript (or should i say ecma script. lol)
and so never said anything. just a big shrug to me