Monthly Contribution Statement dropdown always shows latest month, even when another month is selected

[Miyayes]

Description

In Monthly Contribution Statements, the dropdown list always stays visually stuck on the most recent month, even after selecting a different month. (Underlying data appears to change to the selected month, however.)

Steps to Reproduce

Go to brave://rewards, Monthly Contribution Statements. Choose a previous month. Observe how the dropdown itself continues to display the latest month and does not visually show the selected month.

Expected result:

Should show selected month.

Reproduces how often:

100% of the time. Reproduced by @pes10k and @Miyayes.

Brave version (brave://version info)

Version 1.18.78 Chromium: 87.0.4280.141 (Official Build) (x86_64)

Even after a previous month is selected and the dropdown collapses, January 2021 (or latest month at that time) is always shown.

[LaurenWags]

Verified passed with

Brave | 1.21.52 Chromium: 88.0.4324.152 (Official Build) dev (x86_64)
-- | --
Revision | 6579930fc53b4dc589c042bec9d0a3778326974d-refs/branch-heads/4324@{#2106}
OS | macOS Version 10.15.7 (Build 19H512)

Verified test plan from brave/brave-core#7615.
Encountered and logged #14159 while testing.

Feb 2021	Jan 2021	Dec 2020

---

Verification passed on

Brave | 1.21.62 Chromium: 88.0.4324.182 (Official Build) beta (64-bit)
-- | --
Revision | 73ee5087001dcef33047c4ed650471b225dd8caf-refs/branch-heads/4324@{#2202}
OS | Windows 10 OS Version 2004 (Build 19041.804)

Verified test plan from brave/brave-core#7615.

Feb 2021	Jan 2021	Dec 2020

---

Verification passed on

Brave	1.21.64 Chromium: 88.0.4324.182 (Official Build) beta (64-bit)
Revision	73ee5087001dcef33047c4ed650471b225dd8caf-refs/branch-heads/4324@{#2202}
OS	Ubuntu 18.04 LTS

Verified test plan from brave/brave-core#7615.

Feb 2021	Jan 2021	Dec 2020