Created attachment 8036 [details]
Patch that seems to fix the issue

Hello,
  it seems I have found a bug in busybox implementation of sed utility (version 1.29.3, also in 1.30.1). When using row addressing in sed command in format <addr1>,+N (i.e. apply to N rows following the match of <addr1>), it seems that following rows are processed only for the first match. For following matches, only the first row (matching <addr1>) is processed.
  Example:
- test file:
AAA
    BBB1
CCC
CCC
AAA
    BBB2
AAA
    BBB3
- command: sed -n '/AAA/,+1 p' file
- expected result (GNU sed):
AAA
    BBB1
AAA
    BBB2
AAA
    BBB3
- busybox sed:
AAA
    BBB1
AAA
AAA
  I have just quickly inspected the code and it seems that index of the last line for multiline match is overwritten with computed value relative to the first match and not reset/recomputed for further matches. I created a patch that seems to fix the issue, however I am not entirely confident it is a correct and clean solution.
With regards,
  Vit Lapka