Streaming API "track" with logical "AND" dropping many tweets



I have a single stream containing multiple keywords. My stream contains only keywords and absolutely no users or location combinations. So an as example it looks like:

track=[“kwa”,“kwb”,“kwc kwd”,“kwe”,“kwf kwg”…]

We have both OR and AND combinations. None of the logical ANDs have more than two keywords. The total number of keywords would be around maybe 50 at max which is well within the 400 kwds limit. The trouble is we have notices some substantial tweet drops with the logical AND combinations. Observations:

if from a test account I tweet “kwa” 20 times I get all the tweets
if from a test account i tweet “kwc kwd” (part of stream as logical AND) 20 times I get ONLY 1-2 tweets max
there are no rate limit error messages thrown. Total traffic is hardly 3-4 tweets per second at peak.

I have tested this multiple times at different timespans throughout yesterday but the result remains the same.

Can someone please help me understand if this is by design? If yes, why aint I getting any Rate Limit errors? Were there any issues yesterday?

I would be very grateful if I could get a quick response from you experts.

Many Thanks