The parameter par of ACCRINTM ( https://help.libreoffice.org/Calc/Financial_Functions_Part_One#bm_id3148866 ) and ACCRINT ( https://help.libreoffice.org/Calc/Financial_Functions_Part_One#bm_id3149815 ) should be marked as optional. If they are leaved out 1000 is assumed.
Olivier Hallot committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/help/commit/?id=f9a4ba48ebcb885f1d025aa72e674a3b69c4e576 tdf#97813 optional/required param in ACCRINT*