Practice sessions don't save all words

Memrise Bug Control Web Bugs
1

In Google Chrome, after practice sessions the site stops at the statistics, without showing the practiced words for several seconds, sometimes minutes, clicking “next” doesn’t do anything and I have to do many of the words again.

The console gives these errors:

2raven.js:1483 POST https://api.segment.io/v1/t net::ERR_EMPTY_RESPONSE
(anonymous) @ raven.js:1483
o @ analytics.min.js:9
j.enqueue @ analytics.min.js:7
j.ontrack @ analytics.min.js:7
(anonymous) @ analytics.min.js:7
o.emit @ analytics.min.js:14
(anonymous) @ analytics.min.js:14
o._invoke @ analytics.min.js:2
(anonymous) @ analytics.min.js:14
o.track @ analytics.min.js:1
(anonymous) @ analytics.min.js:14
(anonymous) @ analytics.min.js:1
3…/analytics @ analytics.min.js:1
i @ analytics.min.js:1
e @ analytics.min.js:1
(anonymous) @ analytics.min.js:1
(anonymous) @ analytics.min.js:17
raven.js:1483 POST https://api.segment.io/v1/t net::ERR_EMPTY_RESPONSE
(anonymous) @ raven.js:1483
o @ analytics.min.js:9
j.enqueue @ analytics.min.js:7
j.ontrack @ analytics.min.js:7
(anonymous) @ analytics.min.js:7
o.emit @ analytics.min.js:14
(anonymous) @ analytics.min.js:14
o._invoke @ analytics.min.js:2
(anonymous) @ analytics.min.js:14
o.track @ analytics.min.js:1
(anonymous) @ analytics.min.js:14
trackTestAnswered @ garden-base.js:156
register @ garden-base.js:134
check @ typing.js:156
r @ inheritance.js:52
next_press @ typing.js:84
r @ inheritance.js:52
(anonymous) @ typing.js:54
value @ typing-input.js:50
m @ lodash.compat.js:5759
setTimeout (async)
(anonymous) @ lodash.compat.js:5813
dispatch @ jquery.js:5183
m.handle @ jquery.js:4991
t @ raven.js:445
4raven.js:1483 POST https://www.memrise.com/ajax/learning/register 502 (Bad Gateway)
(anonymous) @ raven.js:1483
send @ jquery.js:9600
ajax @ jquery.js:9206
submit @ register-queue.js:13
register @ garden-base.js:143
check @ typing.js:156
r @ inheritance.js:52
next_press @ typing.js:84
r @ inheritance.js:52
(anonymous) @ typing.js:54
value @ typing-input.js:50
m @ lodash.compat.js:5759
setTimeout (async)
(anonymous) @ lodash.compat.js:5813
dispatch @ jquery.js:5183
m.handle @ jquery.js:4991
t @ raven.js:445

2

Tested on a different computer, it doesn’t happen there.

3

Seems to work for a while, then it starts acting up.
FF seems to work better.

4

in english goddamit

5

Those are what the console gives when memrise hangs up, I’m hoping they’d help the devs trace the cause of the problem, if they ever care to do something about it.