pinnacle kept rejecting my stake but accepted tiny amount at same price

been running into this weird thing lately - tried placing a mid-sized bet, but it just kept getting declined, saying not available. out of curiosity, i lowered the stake to almost nothing and it actually took it right away, still at the same odds. not talking huge amounts here, just way less than my usual.

anyone else run into this when betting certain lines? is it just down to limits being set algorithmically or is there something else going on? i’ve seen it a few times now, usually on less popular markets. curious if you just back off when this happens, or is it ever worth splitting bets into small chunks to get more down?