`im_sv_dumps` produces empty (0-byte) files in tissue simulations

Question

In a tissue opencarp run, imp_region[0].im_sv_dumps creates one file per state variable but every file stays 0 bytes, even though the run completes and 'vm.igb' is written correctly. No warning printed.

## parameters.par ##

num_imp_regions                         = 1

imp_region[0].im                           = tenTusscherPanfilov

imp_region[0].num_IDs                = 1

imp_region[0].ID[0]                      = 1

imp_region[0].im_sv_dumps       = "Cai,D,F,F2,H"

gregion[0].num_IDs                      = 1

gregion[0].ID[0]                        = 1

gregion[0].g_il                         = 0.056

gregion[0].g_it                         = 0.056

gregion[0].g_in                         = 0.056

gregion[0].g_el                         = 0.056

gregion[0].g_et                         = 0.056

gregion[0].g_en                         = 0.056

num_stim                                = 1

stimulus[0].stimtype                    = 0

stimulus[0].strength                    = 100

stimulus[0].duration                    = 2

stimulus[0].npls                        = 1

meshname                                = mesh1/block

simID                                   = 2026-09-07_TT06

tend                                    = 500.0

dt                                      = 100.0

spacedt                                 = 1.0

timedt                                  = 5.0

bidomain                                = 0