Biceps Cramp When Flexed

Hi,
I wonder if I can get some help here (worked pretty good in the past :-):
Lately I am getting biceps cramps (both arms) when I put them (the biceps) in a flexed, isometric position.
I had this happen while doing dragon flags where the biceps are flexed hard pulling me into the bench.
Also happened after cleaning about 85kg and holding the weight on my arms (I am not flexible enough to rest the bar on my shoulders) and it also happen if I simply flex the biceps hard enough (like in front of the mirror…)

Any ideas why it happens or how to fix it?

I am 44 yrs old train heavy with power lifting, olympic lifting, crossfit metcons. Currently doing an olympic lifting cycle

Thanks!